Uwell Caliburn GPP Top Fill XL Cartridge (4 Pack)

The number on the pod is its coil resistance in ohms, and it sets the character of the vape. A lower number runs warmer and looser with more vapour; a higher number runs cooler and tighter with less. Here is the quick guide.

The 1.2ohm is the tightest, coolest and most cigarette-like, kindest on the battery and best paired with a strong 20mg salt. The 0.9ohm is the classic Caliburn mouth-to-lung draw most people reach for. The 0.6ohm runs a touch warmer and looser, and the 0.4ohm is the loosest, a restricted lung draw with the most vapour that makes the most of the G4 Pro's 35W. If in doubt, start with the 0.9ohm.

The reason people stay loyal to the Caliburn line is flavour, and these pods carry Uwell's Pro-FOCS 4.0 coil, the latest version of the flavour-optimisation tech the name is built on. It is tuned to reproduce the e-liquid as accurately as possible, so a fruit tastes like the fruit rather than a vague sweet note, and it holds that clarity across the life of the pod rather than fading after the first day. If you have ever found a pod tasted muddy or flat, this is the part that addresses it.

It also handles a range of liquids well. Pro-FOCS is happy with both nic salts and freebase, so you are not boxed into one type, and it copes with the sweeter dessert and cocktail flavours that gunk lesser coils quickly. The coil is built into the cartridge, so you do not fit coils separately: when the flavour eventually dulls, you simply swap the whole pod.

Two design touches make these pods easy to live with. The first is the top-fill: you lift a cap on top of the cartridge and drip your e-liquid straight in, with no fiddly side stopper to prise out and no mess on your fingers, which is one of the nicer refilling experiences on any pod. The second is Uwell's U2 anti-leak construction, built on ultrasonic welding and a u-shaped airflow channel, which the brand rates at a big reduction in leaking versus older Caliburn pods.

In day-to-day use that means far less of the sticky residue around the pod and device that plagues cheaper kits, and more confidence carrying a filled cartridge in a bag or pocket. The generous 3ml capacity helps too: you fill up less often, so there are fewer chances to overfill or spill, and a full pod lasts most of a day for an average vaper.

A fresh pod needs filling and a short soak before its first use, or the coil can scorch dry. The top-fill design makes it quick.

The resistance you run changes how much nicotine you take in, so it pays to match the two. A tight 1.2 or 0.9ohm pod makes less vapour, so a 20mg salt feels right and a bottle lasts well. The looser 0.6 and 0.4ohm pods push much more vapour, especially on the G4 Pro at 35W, and since nicotine rides in that vapour you take in more per puff, so a 20mg salt can feel harsh and disappear quickly.

The simple rule is to drop the strength as you drop the resistance: most people are happy on 20mg with the 0.9 and 1.2ohm, move to 10mg on the 0.6ohm, and use a low-strength salt or a 3 to 6mg freebase on the 0.4ohm. Get that pairing right and the Caliburn stays as smooth as its flavour reputation suggests, whichever pod you have in.

Refillable pods are what make a Caliburn cheap to own after the upfront kit price. At £43.99 for 20 pods, about £2.20 each, and with each lasting a week or two of refills, the running cost sits far below a disposable habit. Add a 10ml bottle of salt at a pound or two, which refills a 3ml pod a few times over, and a single pod plus a bottle covers a couple of weeks for less than the price of one single-use bar.

Buying a box of 20 also means you always have a spare to hand, and because the pods fit the wider GPP-compatible Caliburn family, the box stays useful even if you change devices later. Keep one pod in use and the rest in the drawer, prime each new one properly, and the only thing you ever bin is the small spent cartridge.