Here is a thing that happens with the FEV V4.5S+ more often than it should.

A customer orders the tank, waits for it, builds it, fills it, takes one pull, and thinks: this is tighter than I expected. Or the opposite - it is looser than they hoped. Either way they go looking for the fix and find a wall of parts with names like "Long AirPin" and "Peek Chamber Reducer V2" and "Dual Airflow Part Upgrade" and no explanation of which does what.

We sell all of those parts. So we wrote down what each one actually does.

First, the thing nobody tells you about the stock air pin

The FEV V4.5S+ comes set up for a fairly tight mouth-to-lung draw. If you are used to anything under 1.0mm - and a lot of long-time MTL vapers are - the stock setup will not be tight enough.

This is not a niche complaint. On a long-running UK vaping forum, a vaper looking at the V4.5S+ put it plainly:

"Also interested in the draw, smallest is a 1.2mm, I'm usually in the 1.0mm or below territory."

That is the gap. The tank is good. The stock air pin is one size, and if your size is smaller, you need a part.

Every FEV air pin we stock, and what it does

Air pins are measured by the hole diameter. Smaller hole means a tighter, more cigarette-like draw. Bigger hole means more air, cooler vapour, and eventually restricted-lung territory.

Size  |  What it feels like  |  Who it suits

0.8mm  |  Very tight. Close to a cigarette filter.  |  Old-school MTL, high-nic salts, stealth vaping

0.9mm  |  Tight, but with a little more room  |  Most classic MTL vapers

1.0mm  |  The common MTL reference point  |  People who say "1.0 is my number"

1.2mm  |  Stock on most V4.5S+ builds  |  Loose MTL, first-time FEV owners

1.4mm  |  Noticeably airier, still MTL  |  Loose MTL, cooler vape

1.8mm  |  Restricted lung  |  RDL vapers

2.0mm  |  Open restricted lung  |  RDL and light DL

The four ways to change your draw (and what each costs)

1. Swap the air pin - cheapest, most direct

The Ulton Long AirPins 4-pack gives you 0.8mm, 0.9mm, 1.0mm and 1.2mm in one bag for $2.99. If you are not sure where you land on the scale, this is the sensible starting point - you get four sizes and you can find your number in an evening.

If you already know you want something bigger, single pins are $1.99 each:

• YFTK Long AirPin 1.2mm
• YFTK Long AirPin 1.8mm
• YFTK Long AirPin 2.0mm

One detail worth knowing: the Ulton 4-pack is listed as compatible with YFTK, Ulton, SXK and original FEV V4.5S+ / V4.5. Cross-brand air pin fit is one of the few places on this platform where the parts really do interchange.

2. Change the intake cover - more air, less fiddling

The YFTK AFC Kit V2 ($14.89) is a different approach. Instead of one pin in one hole, you get an intake cover and two AFC rings - an MTL ring and a DL ring - with inlet holes in 1.0, 1.2, 1.4, 1.6 and 1.8mm, two of each. With the DL ring fitted you can open the draw up far beyond what a single pin allows.

This is the part to buy if you want the FEV to do double duty - tight MTL in the morning, looser in the evening - without swapping metal.

3. Add a chamber reducer - for flavour, not airflow

This is the part most people misunderstand. The ULTON PEEK Chamber Reducer V2 ($5.79) does not make the draw tighter. It reduces the chamber volume so the vapour is denser and the flavour more concentrated. It installs where the airflow control screw sits.

And here is the honest caveat, straight from the product page: it is listed for original FEV V4, V4.5S and V4.5S+, plus Ulton and YFTK V4.5S+ - and the page says outright that compatibility with other FEV atomizers is not guaranteed because of tolerance differences. It works on 1:1 FEV. If you have an odd clone, ask before you buy.

4. Add a dual airflow part - the DL conversion

The Ulton FEV V4.5S+ Dual Airflow Part ($7.99) converts the tank toward direct-lung. It is 23mm across and 23mm tall, fits the V4.5S+, and the product page notes it gives better taste richness compared with the standard V4.5S+ setup.

If you want an FEV that can do proper DL, this plus the 2.0mm pin is the combination.

The other thing that bites new FEV owners: flooding

Air pin choice is the easy problem. Wicking is the one that actually ruins evenings.

On the same forum, a new FEV owner described exactly this:

"Got my FEV today and it's not been the best experience regarding wicking. Have a 2.5mm 1.3ohm spaced coil quite a bit of cotton buy the deck ends up flooding all the time."

In a separate thread, another owner wrote:

"Struggling with my clone 4.5S+. First couple of attempts were spot on, but since then no matter how much or how little cotton I use ... the deck floods to the point the liquid seeps into the air hole."

A forum administrator who had answered this question many times replied with the single most useful piece of FEV advice we have seen:

"Have you got these two? Without these you'll have all manner of floods."

He was talking about the wicking inserts - the small metal tubes that sit in the deck and feed liquid up to the cotton. The FEV does not work like a normal RTA. It does not rely on you getting the cotton density exactly right in a juice channel. It relies on those inserts meeting the cotton at the right height. Miss that and the deck floods no matter how carefully you wick.

The same administrator described his method: pack the cotton reasonably tight into a 3mm coil, cut it slightly short of the deck width, fluff it gently without thinning it much, and look for the marks the juice pipes press into the cotton - that is how you know it is making contact.

Stacking parts: three budgets that actually make sense

Budget 1 - "find my draw" ($4.98)

The four-size air pin pack. Nothing else. Run each pin for a day, decide your number, and you are done. This is the correct first purchase for anyone new to the platform.

Budget 2 - "make it taste better" ($8.28)

The air pin pack plus the replacement glass tank tube ($2.49). Spare glass is not optional on a 23mm tank that lives in a pocket - and this particular tube fits SXK, YFTK and ULTON versions, which is unusually generous.

Budget 3 - "full FEV" ($35.98 and up)

Start with a complete tank rather than a pile of parts. The YFTK Ti FEV V4.5S+ is $35.98 in titanium - the chimney is stainless steel but the body is Ti, which keeps it at 57g for a 73mm tank. It ships with two 316 stainless steel wicks and a pin set covering a sealed plug, two 0.8mm, two 0.9mm, one 1.2mm, one 1.4mm and one 2.0mm.

That package is why the titanium version is worth the money for a first FEV: you get the deck, the wicks and nearly the whole air pin range in one box, so you are not ordering three separate parts to find out whether you like the platform.

Buying the right FEV for you

If you want  |  Get this  |  Price

The classic FEV, lightest possible  |  YFTK Ti FEV V4.5S+ - 23mm, 73mm, 57g, 4.5ml  |  $35.98

A shorter, 2ml FEV in steel  |  YFTK FEV V6 - 23mm, 2ml, 40g, 316SS  |  $24.98

To fix the draw on a tank you already own  |  Ulton Long AirPins 4-pack - 0.8/0.9/1.0/1.2mm  |  $2.99

More flavour from an existing build  |  ULTON PEEK Chamber Reducer V2  |  $5.79

To convert to direct lung  |  Ulton Dual Airflow Part + 2.0mm pin  |  $7.99 + $1.99

A spare deck to build on  |  FEV V4.5S+ Improved Build Deck - fits 5 FEV variants  |  $8.90

FAQ

Will a YFTK air pin fit my SXK FEV?
Yes - the Ulton 4-pack is listed as compatible with YFTK, Ulton, SXK and original FEV V4.5S+ / V4.5. Air pins are the one part where cross-brand swapping is reliable.

Will the PEEK chamber reducer fit my no-name clone?
Maybe not. The product page states it is not guaranteed on FEV atomizers other than the listed ones because of tolerance differences, and that it works on 1:1 FEV. If you are unsure what clone you have, email us before ordering.

My FEV floods no matter how much cotton I use. Is it broken?
Probably not. Check that both wicking inserts are installed and that your cotton is sitting directly over the coil clamp screws, in line with the two liquid feed tubes. That alignment matters more than cotton quantity on this deck.

Can I make an FEV into a direct-lung tank?
Yes, with the dual airflow part plus the 2.0mm pin, or with the AFC Kit V2 and the DL ring. It will not become a cloud tank, but it opens up into proper restricted lung.

Which glass fits which FEV?
The ULTON replacement glass tube (outer 20mm, inner 18mm, 7mm tall) is listed for SXK, YFTK and ULTON V4.5S+. The SXK version is listed for SXK and YFTK. Beyond that, check the product page rather than assuming.

Related reading

• What 2FDeal customers say
• All FEV / Flash e-Vapor products
• All rebuildable tank atomizers
• Replacement tanks and upgrade kits
• New arrivals
• Shipping and tracking

Shop the full FEV range at 2FDeal - parts, tanks and the air pins that make the platform yours.