Uwell Caliburn G4 Pro KOKO Pod Kit Cosmic Gray

Overview

The Uwell Caliburn G4 Pro KOKO Pod Kit Cosmic Gray by Uwell in Cosmic Gray at 0mg. Free UK delivery over £20, same-day dispatch on weekday orders before 4pm.

Uwell Caliburn G4 Pro KOKO Pod Kit overview

The Uwell Caliburn G4 Pro KOKO Pod Kit is a compact, refillable pod vape from a brand that has spent years building small, pocketable hardware around a long-running pod ecosystem. It is a reusable device. You charge the battery, fill a pod with the e-liquid you prefer, and replace the pod when the coil wears out. It is not a disposable, and in the UK that distinction matters more than it used to, because single-use vapes have been banned from sale in Great Britain since 1 June 2025. A refillable kit like this one sits on the right side of that change, and it works out cheaper to run over time.

The Caliburn name covers several generations of hardware, and the G4 Pro sits in the middle of the line. It is more capable than the stripped-back Lite models, yet far smaller and simpler than an adjustable box mod. For a lot of adult smokers moving across to vaping, that middle position is the whole appeal: a tight, cigarette-like draw, a body small enough to disappear into a jeans pocket, and no wattage menus to learn before you can get started.

There are nine variants in this family, and they share the same internals. The differences are cosmetic, so the real buying decision is whether the platform suits the way you vape, and only then which finish you would rather carry. This guide covers what a UK buyer should know before ordering:

• How the pod and coil system behaves, and what the KOKO label tells you about compatibility
• What to expect from vapour, throat feel and flavour
• Battery capacity, charging habits and realistic daily use
• Which nicotine strength to pick, including the UK 20mg/ml cap
• Who the kit suits, who should look elsewhere, and how it compares with rival pod kits
• Setup, troubleshooting, recycling and delivery

A note on figures. Uwell revises hardware and packaging between production batches, so the specifications quoted below are typical values rather than guarantees. Where the product listing or the printed card in the box differs from this guide, trust the listing and the card. Nicotine is addictive, and this product is for adults aged 18 and over who already use nicotine.

How the pod and coil system works

The G4 Pro is a closed-pod system, which is the simplest design in vaping. The pod holds the e-liquid and contains the coil. It clicks into the battery body, makes electrical contact through small connectors, and is drawn on directly. There is no separate tank, no coil to prime with tools, and no wire to wrap. When the coil eventually wears out you replace the whole pod, not a component inside it.

Uwell builds its pod coils around a wide, flat heating surface rather than a thin round wire wrapped in cotton. The reasoning is straightforward. Heat spreads across more of the wick, liquid vaporises more evenly, and there is less chance of one hot spot scorching the cotton. In practice that tends to show up as steadier flavour across the life of a pod and fewer sudden burnt hits, although no coil design removes dry hits if the pod is run empty or primed badly.

What the KOKO label means for compatibility. Uwell has sold several pod families under the Caliburn banner, and they are not all interchangeable. KOKO belongs to one of those families, and the pod you buy has to match the pod format your device was built for. Before ordering spares, match the pod to the generation named on the listing. If you are unsure, check the compatibility notes on the replacement pod page or ask before buying. A pod from the wrong family will not seat properly, and forcing one in is a quick way to damage the connectors.

Caliburn-family pods are sold in several resistances, typically spanning roughly 0.4 to 1.2 ohm depending on the pod family. Resistance changes the character of the vape more than any other single variable:

• Lower resistance (around 0.4 to 0.6 ohm): warmer vapour, more of it, faster liquid use and a looser draw. This suits a lower nicotine strength.
• Mid resistance (around 0.8 to 0.9 ohm): a balanced option with a moderate draw, enough flavour density to be satisfying, and reasonable economy.
• Higher resistance (around 1.0 to 1.2 ohm): cooler vapour, a tighter draw closer to a cigarette, and better economy. This suits nicotine salts at higher strengths.

If you are replacing a worn pod, buying the same resistance is the safest route. If you are changing resistance on purpose, alter one thing at a time, so you can tell which change you are actually tasting. Changing pod and liquid together makes it hard to judge either.

Performance and vapour delivery

Pod kits are not rated in puffs the way disposables are, because the number of draws depends on the liquid you use and how you vape. The more useful way to think about it is capacity. A refillable pod in a UK-sold kit holds up to 2ml, the legal maximum for a refillable tank or pod in the UK, and one fill typically delivers somewhere in the region of 200 to 400 draws. Lower resistances burn through liquid faster and land near the bottom of that range. Higher resistances stretch further. A 10ml bottle fills roughly five pods, so planning on 1,000 to 2,000 draws per bottle is reasonable.

The draw itself is the main reason people choose the Caliburn format. It is a mouth-to-lung design: you draw into your mouth, pause briefly, then inhale. Airflow is restricted compared with a sub-ohm tank, so the sensation is closer to drawing on a cigarette than breathing through a straw. For anyone coming off tobacco, that familiar tightness is often what makes the switch feel manageable rather than strange.

Vapour production is modest by design. This is not a cloud-chasing device, and anyone expecting dense plumes should look at a sub-ohm kit instead. What you get is a consistent, flavour-led hit with a throat sensation that depends mostly on nicotine strength. Nicotine salts at 20mg/ml feel smoother than freebase nicotine at a comparable strength, although the nicotine delivery is stronger, which is why strength choice matters.

Consistency across a pod's life is where a pod system either earns its place or loses it. In normal use, vapour and flavour should hold steady until the liquid drops towards the wicking ports. When a coil nears the end, the decline is gradual: flavour dulls first, then a faint toasted note appears. That is your cue to change the pod rather than push through. Sweet liquids, particularly desserts and heavily sweetened fruit blends, caramelise on the coil faster and shorten its life. Cleaner profiles such as menthol, tobacco and lighter fruit tend to last longer.

Ramp-up is quick, with vapour arriving in the first second of a draw rather than after a delay. Chain-vaping, taking draw after draw without a pause, can outrun the wick, so leave a few seconds between hits if you notice the vapour thinning. Slow, steady draws of two to four seconds suit this format better than short sharp pulls.

Flavour profile and the nine colourways

The device has no flavour of its own. Everything you taste comes from the e-liquid and the coil heating it, so flavour decisions with this kit come down to choosing a liquid that suits a tight, mouth-to-lung draw. Nicotine salt liquids are the usual choice because they hold flavour clearly at the modest power a pod kit runs at. These are the profile families that work well in this format, and what to expect from each:

• Blueberry and berry ices: bright, familiar and forgiving. Berry blends keep their identity across every resistance.
• Strawberry and watermelon: juicy and light enough for all-day use. The sweetness is manageable on a coil and ages a pod less than creamy blends.
• Mango and peach: rounder tropical flavours that benefit from a warmer, lower-resistance pod, where the sweetness shows fully.
• Menthol and peppermint: clean and long-lasting on the coil. A sensible rotation option when you want a reset between sweeter flavours.
• Classic tobacco: the obvious pick for people leaving cigarettes behind. It tends to reward higher-resistance pods and salt-strength nicotine.
• Cola and soda: sharp and fizzy with a little sweetness, and it suits mid-resistance pods.
• Vanilla and custard: richer and heavier. These leave more residue on the wick, so expect a shorter coil life.
• Apple and pear: crisp and light, a good alternative to berry blends if those start to feel samey.

One practical rule applies to all of them. Thick, high-VG liquids can be slow to soak through the wicking ports of a small pod. Choose a 50VG/50PG nicotine salt, or another liquid sold for pod systems, and the pod will saturate quickly and run reliably. Shortfills and very thick 70VG blends are made for sub-ohm tanks and tend to starve a pod coil.

The nine variants in this family are colour choices, not flavours. Finishes sold across the G4 Pro line have included Desert Gold, Fantasy Pink, Frost White, Ink Blue, Iron Gray, Light Green, Pearl Silver and Stripe Black. The hardware is identical, so choose the finish you like. If you want variety, keep a second pod filled with a different profile and swap between them. Rotating flavours is the simplest fix for the palate fatigue that sets in when you vape one taste all day.

Design and build quality

The G4 Pro is a slim, rounded rectangle designed to be held more like a lighter than gripped like a mod. It is light enough to forget about in a pocket, small enough to sit in a closed hand, and shaped so the mouthpiece rests comfortably between the lips without an awkward angle. If you have owned a Caliburn before, the proportions will feel familiar, and that is deliberate on Uwell's part.

The body has a coated finish, and how that finish ages depends on the colourway. Light colours such as Frost White and Pearl Silver look sharp when new but show fingerprints and pocket scuffs quickly. Darker finishes such as Iron Gray and Stripe Black hide wear better and look plainer. Mid-tone options like Desert Gold, Ink Blue and Light Green sit in between. None of this affects performance, but if the device is going to live in a bag alongside keys and coins, a darker finish is the practical choice.

Points worth checking when your kit arrives:

• Pod seating: the pod should click into place with a firm fit and no sideways rock. A wobbling pod usually points to debris on the contacts or the wrong pod family.
• Liquid window: you should be able to see the liquid level in the pod, which makes it easy to refill before the wick runs dry.
• Charging port: a USB-C port at the base should sit flush and accept the cable without force.
• Mouthpiece: a moulded, slightly flattened tip that stays comfortable over long sessions.

Build quality is what you would expect from an established brand at this price tier: solid body, tidy seams, and a pod that does not feel flimsy in the hand. The honest caveat is that the weakest point of any pod system is the pod itself. It is thin plastic with a silicone seal, and it is the part most likely to cause trouble if it is overfilled, dropped, or left in a hot car. Handle the pods with a little care and the body will outlast many of them.

Because the device is sealed and has no user-serviceable parts, there is nothing to tighten, unscrew or rebuild. That keeps maintenance close to zero, and it is a real advantage over refillable tanks for anyone who simply wants the thing to work.

Battery and charging

The G4 Pro is generally listed with a battery in the 750mAh class, charged through a USB-C port. Check the listing for the exact figure on the unit you order. To put that capacity in useful terms, a 750mAh cell stores roughly 2.8Wh of energy. At the modest output a pod kit uses, that is enough for somewhere around 250 to 350 draws per charge, which is very close to the number of draws in a single 2ml pod. In practice, a full charge and a full pod tend to run out at about the same time.

What that means day to day depends on how heavily you vape:

• Light use (around 100 to 150 draws a day): charge every two to three days, and one pod will last about two days.
• Typical use (around 250 to 350 draws a day): charge once a day, usually overnight, and refill about once a day.
• Heavy use (400 or more draws a day): expect to top up during the day, and carry a second pre-filled pod so you are not waiting on a refill.

A full charge from empty usually takes in the region of an hour using a standard 5V adapter. A phone charger, laptop USB port or similar low-power source is ideal. There is no benefit to a high-wattage fast charger, because the device only takes what it needs and a poor-quality unit adds risk rather than speed.

A few habits keep the battery healthy and safe:

• Use the supplied cable or a reputable replacement, and stop using any cable with a frayed or bent connector.
• Do not charge on a bed, sofa or other soft surface, and do not leave it charging unattended for long periods.
• If the device becomes noticeably hot while charging, unplug it and let it cool.
• Keep the port dry. If liquid has found its way into it, let the device air-dry fully before plugging in.
• Avoid leaving it in direct sun or a hot car, which is hard on lithium cells and on the pod seal.

The battery is not user-replaceable. At the end of its working life, which for most owners is a year or two of regular use, the whole device goes for recycling rather than in the bin, because lithium cells are a fire risk in household waste and refuse lorries.

Choosing a nicotine strength

UK law caps e-liquid nicotine strength at 20mg/ml, equal to 2%, and limits refillable bottles to 10ml. That cap is the same ceiling that applies to disposables sold before the ban, and it applies to every bottle you will fill this kit from. You will not find a legal 50mg salt in a UK shop, and you should be wary of anything claiming to be one.

Within that limit, the choice comes down to two things: how much you currently smoke or vape, and which pod resistance you are using. The two interact, so it helps to decide them together.

• 20mg/ml nicotine salt: suits adults who smoked around 15 or more cigarettes a day, or who find lower strengths leave them reaching for a cigarette. It pairs well with a higher-resistance pod (1.0 to 1.2 ohm), which delivers it more gently.
• 10mg/ml to 12mg/ml: a sensible middle for lighter smokers, for people stepping down from 20mg, and for anyone who finds 20mg harsh. It works well in 0.8 to 1.0 ohm pods.
• 3mg/ml to 6mg/ml: typically freebase nicotine, aimed at people who are already well down the nicotine ladder or who vape mainly for habit and flavour. Freebase at low strength is better suited to a lower-resistance pod.
• 0mg/ml: nicotine-free liquid, for flavour only or for the final stage of stepping down.

The rule of thumb is inverse. High nicotine goes with high resistance, and low nicotine goes with low resistance. A 20mg salt in a 0.4 ohm pod delivers a lot of nicotine per draw, and most people find that harsh or even lightheaded. At the other extreme, 3mg freebase in a 1.2 ohm pod can feel thin and unsatisfying, and it leaves some users chaining draws to compensate.

If you are unsure, start one step lower than you think you need and move up if you find yourself reaching for cigarettes. It is easier to increase strength than to undo the effects of too much. Nicotine is addictive, and the aim of most adult users is to hold or reduce their intake over time. If you are pregnant, have a medical condition, or take medication, speak to a pharmacist or doctor before using any nicotine product. NHS stop smoking services can also help if you are trying to quit altogether.

Who the G4 Pro KOKO kit suits, and who should skip it

No pod kit suits everybody, and it is better to know where this one fits before spending money. It is built around a tight draw, modest vapour and low maintenance, and the people who get the most out of it are those who want exactly that.

It is a good fit for:

• Adult smokers switching to vaping. The restricted, mouth-to-lung draw is the closest thing to a cigarette in this category, and the simple operation means there is little to learn.
• People who want something pocketable. It is small and light enough to carry all day without a bulge.
• Anyone leaving disposables behind. With single-use vapes banned in Great Britain, a refillable kit gives you the same convenience with lower running costs and much less waste.
• Buyers who like choosing their own liquid. You pick flavour, strength and brand rather than being locked to a pre-filled puff count.
• Vapers who want a platform with replacement pods that are easy to find. Caliburn is widely stocked in UK shops, so spares are rarely a problem.

You should look elsewhere if:

• You want big clouds. A sub-ohm kit or a higher-power device is the right tool, not a restricted pod system.
• You want to adjust power finely. The G4 Pro is built to be simple, and an adjustable-wattage mod will give you more control.
• You vape very heavily on thick, high-VG liquids. A small pod will struggle with thick liquid, and you would be refilling constantly.
• You are under 18 or have never used nicotine. Nicotine products are not for non-smokers and are illegal to sell to under-18s in the UK.
• You dislike any kind of upkeep. Even a simple refillable needs filling, priming and the occasional pod change. If that is a deal-breaker, the realistic alternative is a pre-filled pod system, which costs more per millilitre.

A fair summary is that this is a straightforward, dependable daily device for people who value simplicity over customisation. If that describes you, the platform is a sound choice. If you are already comfortable with adjustable devices and want more power or airflow control, you will probably find it limiting within a few weeks.

How to fill, prime and use it

Setting up a refillable pod properly takes five minutes and prevents nearly every common problem. Follow these steps the first time, and again with every new pod.

• Step 1. Charge the device. Give it a full charge before first use if the battery is not already topped up, using the cable and a standard 5V adapter.
• Step 2. Remove the pod and take off any protective film. New pods often arrive with a seal or tape over the airflow and fill port, and the pod will not work until it is removed.
• Step 3. Open the fill port. It is usually a silicone plug on the side or base of the pod. Pull it back gently and keep it clean.
• Step 4. Fill slowly, avoiding the central airflow tube. Angle the bottle tip against the side wall of the fill port and let the liquid run down. Stop at or just below the maximum line. Overfilling is the leading cause of leaks and gurgling.
• Step 5. Press the plug back in firmly. It should sit flush with no gaps.
• Step 6. Wait and prime. Stand the pod upright for 5 to 10 minutes so the liquid soaks into the wick. A dry wick is destroyed by the very first draw, and that damage cannot be reversed.
• Step 7. Click the pod into the device. Seat it firmly until it stops.
• Step 8. Take a few gentle draws. Start with two or three short, light pulls to bring the liquid to the coil, then settle into normal use.

The device is draw-activated, so there is no firing button to manage in normal use. You simply draw on the mouthpiece and an LED indicates activity. If a puff runs too long, a built-in cut-off typically stops the output after about eight to ten seconds, so a stuck draw is not a worry. Flashing indicator patterns vary, and the printed card in the box explains what each one means for your unit.

Habits that extend pod life:

• Refill when the liquid drops to the level of the wicking ports, and do not draw on a nearly empty pod.
• Keep the pod upright when storing, and keep the device away from heat.
• Wipe the pod base and the device contacts with a dry cloth every few days, because condensation and liquid film interfere with the connection.
• When changing flavour, use a fresh pod where possible, since flavours linger in a used wick and mix.

Troubleshooting common problems

Most complaints about pod kits come down to handling rather than a fault with the device. These are the common issues and what usually fixes them.

• Burnt or toasted taste: almost always a dry or worn wick. Check the liquid level, and if the pod has been in use for a couple of weeks, replace it. Sweet liquids shorten coil life, so a burnt taste after a short time on a creamy dessert flavour is normal rather than a defect.
• Leaking from the pod or the device: usually overfilling, a loose fill plug, or heat. Fill to just under the line, press the plug in fully, and keep the device away from hot places. If it persists, the pod seal may be damaged and the pod should be replaced.
• Gurgling or spitting: liquid has pooled in the airflow channel. Remove the pod, tap it gently on a tissue, wipe the mouthpiece, and refit it. Overfilling is the usual cause.
• Weak vapour or thin flavour: the wick may be starved, the liquid too thick, or the coil nearing the end of its life. Prime again, switch to a thinner 50/50 liquid, or fit a new pod.
• No firing or an unresponsive device: check the battery first, then check the pod is seated and the contacts are clean. Wipe them with a dry cotton bud, never with liquid.
• Pod will not click in: it may be the wrong pod family, or debris may be on the contacts. Do not force it, and check the compatibility details on the listing.
• Battery draining quickly: a lower-resistance pod draws more power. A very old battery also loses capacity, and a quick-draining battery after a year or more of daily use may just be wear.
• Flavour seems flat: palate fatigue is common on a single flavour. Rotate to a different profile for a few days and the original usually tastes right again.

If you have worked through these and the device still does not behave, stop using it and contact the shop with your order number and a short description or photo. Do not attempt to open the casing, and never continue using a device that overheats, swells or smells of burning.

Value for money and how it compares with other pod kits

The cost of a pod kit has two parts: the one-off price of the hardware, and the running cost of pods and liquid. The hardware is a modest outlay, and the running cost is where a refillable device pulls ahead of disposables. A 10ml bottle of nicotine salt typically costs a few pounds and fills around five pods. A replacement pod usually costs a few pounds more and, depending on flavour and resistance, lasts around one to two weeks of regular use. Add the two together and a regular vaper will usually spend noticeably less per month than someone buying a new disposable every few days. Check the current listing price, because it changes with promotions.

Value also depends on how long the platform stays available. The Caliburn line has been stocked widely in UK shops across several generations, which makes it easier to find pods years after buying the device. That counts for more than a small saving on a kit whose consumables disappear in eighteen months.

Here is how it stacks up against rival pod kits, with the caveat that specifications shift between revisions:

• Vaporesso XROS series: a strong competitor with a larger battery in the 1000mAh class on some models, and mesh-coil pods with several resistances. If you want more battery life and slightly more flavour range, it is worth comparing. The Caliburn tends to be slimmer and simpler.
• OXVA Xlim series: offers adjustable airflow on several models, which the Caliburn does not emphasise. If you like adjusting the draw from tight to looser, the Xlim is the better fit. The Caliburn is the more minimal option.
• SMOK Novo series: widely sold, with a large pod catalogue and often keen pricing. Build and flavour are comparable, and the choice often comes down to which pod resistances you prefer.
• Geekvape Wenax and similar compact kits: competitive on size and price. They are worth looking at if you want a very small body, though the choice of pods and their availability in UK shops can be narrower.
• Pre-filled pod systems: simpler still, but you pay more per millilitre and are limited to the flavours the maker releases.

None of these is a clear winner for every vaper. The G4 Pro suits people who want a slim, familiar, low-fuss device and a pod range that is easy to buy in the UK. If your priorities are maximum battery or adjustable airflow, one of the alternatives may suit you better, and it is worth being honest with yourself about which of those matters more.

UK rules, recycling, authenticity and delivery

A few UK-specific points are worth knowing before and after you buy.

Age and law. You must be 18 or over to buy nicotine vaping products in the UK, and this shop will ask for age verification. Refillable pods are limited to 2ml in capacity, e-liquid bottles to 10ml, and nicotine strength to 20mg/ml. Single-use vapes have been banned from sale in Great Britain since 1 June 2025, which is why a rechargeable, refillable kit like this one is the lawful and economical route for many vapers who previously used disposables.

Recycling. Do not put any vape device, pod or battery in household waste or the recycling bin. Lithium batteries can ignite when crushed in refuse vehicles, and the fires are a real problem for councils. Instead:

• Return the device to a retailer that sells vapes. UK shops selling electrical items are expected to offer take-back for small electrical waste, so ask the shop where you bought it.
• Use a household waste recycling centre, which has a small electricals or battery drop-off point.
• Look for a vape or battery recycling bin at larger supermarkets and electrical chains.
• Empty the pod and let it dry before dropping it off, and keep used pods away from children and pets.

Authenticity. Uwell is widely counterfeited because Caliburn sells in high volume. Fake pods in particular can leak, taste wrong, or fail to match the printed resistance. Buy from a reputable UK retailer, check packaging for security features, and be suspicious of prices far below the market. If a pod does not look or feel right, stop using it.

Delivery and returns. Orders are dispatched within the UK, and at the time of writing delivery is free on orders above a set threshold, with a same-day dispatch cut-off on working days. An adult may be required to sign for the parcel in line with age-verification rules. For faulty or damaged items, contact the shop promptly with your order number and photos. Your statutory rights under the Consumer Rights Act 2015 apply, although for hygiene and safety reasons opened e-liquid and used pods are generally not returnable unless they are faulty. Always check the returns policy on the site for the current terms.