Infinity Lean 20K Review: Ultra-Thin With Three Power Modes

The Infinity Lean 20K is the thinnest device in our 20K lineup and the cheapest at $20.99. It packs a 6mL tank, a 650mAh USB-C battery and three power modes into a body that disappears in a jeans pocket. After running one for a few weeks, here is what stands out — and where it falls short.

Specs at a glance

Spec	Infinity Lean 20K
Rated puffs	20,000
E-liquid	6mL, prefilled
Nicotine	20mg/mL (2%)
Battery	650mAh, USB-C
Modes	Boost / Smooth / Eco
Price	$20.99
Flavours	14

Who it is for

This is a device for someone who wants a 20,000-puff lifespan without carrying something the size of a phone. It suits a pocket, a jacket and a commute, and it suits a vaper who would rather pay $20.99 and replace the device than pay more and treat it like equipment.

It is not the right pick if airflow adjustment matters, or if you would rather charge once a week than every few days.

Build and feel

At roughly the size of a lighter, the Lean is the most pocketable 20K device we sell. The body is matte, the mouthpiece is comfortable, and the side screen is small but readable: battery percentage, e-liquid level and the active mode. It does not feel cheap — but it also does not feel like a $27 device, and that is the point.

Two details are better than the price suggests: the matte finish does not show fingerprints the way gloss bodies do, and the screen sits on the side rather than the face, so you can read it without turning the mouthpiece towards you.

The three modes actually matter

Boost, Smooth and Eco are not cosmetic. Boost gives the strongest flavour and warmest vapour but drains the battery and the tank fastest. Eco cuts output noticeably — you get more puffs, but the flavour is flatter. Smooth is the sensible default and what most people will leave it on.

In practice, Eco stretched a full tank to roughly 20% longer than Boost in our testing, at the cost of a lighter hit. If you vape heavily, that trade is worth it.

Mode	Flavour and warmth	Tank and battery use	Best for
Boost	Strongest, warmest	Fastest	Short sessions, maximum flavour
Smooth	Balanced	Middle	Everyday default
Eco	Lighter, flatter	Slowest	Stretching the last of a tank

The mode you leave it in is a decision about how many puffs you get. Boost spends the tank faster for a better experience per puff; Eco does the reverse.

Charging and battery life in practice

The 650mAh cell is the one place where the thin body costs you something. On Smooth it is fine — a charge every few days with normal use. On Boost, with long draws, expect to look for a cable more often than you would with a bigger device.

Because the screen shows a percentage, charging is predictable: you can top up at 30% instead of waiting for the device to die mid-session. USB-C means your phone cable works, so there is nothing extra to carry.

Flavour range

The 14 flavours cover the basics well: Watermelon G, Grape, Lychee Ice, Wild Berries, Blue Razz and Extreme Mint are the standouts. The iced versions are medium-cool rather than freezing, which keeps the fruit readable. See the full lineup on the Infinity Lean 20K collection.

The spread is broad rather than experimental: a single-note mint, several fruit singles, a couple of berry blends and a small group of iced versions. If you want no cooling at all, Watermelon G and Wild Berries are the safe picks.

Where it falls short

• No airflow switch. Unlike the WAKA Optimus 120K, the draw is fixed — you cannot switch between MTL and RDL.
• Small battery. 650mAh means a charge every few days if you use Boost.
• Flavour fade late in the tank. The last 10% of the 6mL tastes noticeably weaker, which is normal for a wick this small.

None of these is a defect. They are the trade-offs that buy the thin body and the $20.99 price; for most daily vapers the fixed draw is the only one that matters.

How it compares with the WAKA Optimus 120K

Spec	Infinity Lean 20K	WAKA Optimus 120K
Price	$20.99	$31.99
Rated puffs	20,000	120,000
E-liquid	6mL	30mL
Battery	650mAh, USB-C	850mAh, USB-C
Draw control	Three power modes, fixed draw	Dual airflow, MTL and RDL
Nicotine	20mg/mL (2%)	1.8%
Flavours	14	10

The comparison is less lopsided than the puff counts suggest. The Optimus costs about half again as much up front and lasts six times longer, so on cost per puff it wins — but it is the device you leave on a desk, not forget in a pocket. The Lean wins on size and entry price.

Value math

At $20.99 for 20,000 rated puffs, the Lean works out to about $0.001 per puff — the same as a $26.99 AiRMEZ Mars and cheaper than most 5K devices. For a daily vaper that is roughly $20–$25 a month.

If you want a bigger tank, the 100K tier drops the monthly cost to $12–$16. If you want a screen and dual airflow at 20K, compare the rest of the 20K lineup.

Cost over 12 months

Twelve months at $20–$25 a month is roughly $240–$300, device cost only. That is the number to weigh against the 100K tier at $12–$16 a month, which lands near $144–$192 over the same period.

The gap is real but modest — around $100 a year — and it comes with a much larger device. If you want the smallest thing that lasts three to five weeks, the Lean gets you there.

Common mistakes buyers make

• Leaving it on Boost permanently. It is the fastest way to drain a 650mAh battery and a 6mL tank, and it is not how the device is meant to be used daily.
• Judging the battery before trying Smooth. The mode you use changes runtime more than anything else about the device.
• Buying three flavours at once. Start with one, finish the tank, then commit.
• Expecting airflow control. The draw is fixed; if you want MTL and RDL in one device, this is not it.
• Letting it die mid-tank. The screen exists so you can charge early.

Verdict

The Infinity Lean 20K is the best value 20K device we stock: thin, light, rechargeable, with modes that genuinely change the experience. Buy it if you want a pocketable daily device on a budget; skip it if you need airflow switching or the biggest possible tank.

Frequently Asked Questions

How many puffs does the Infinity Lean 20K really deliver?

It is rated to 20,000. In Eco mode with shorter draws you get close to that; in Boost mode expect closer to 14,000–16,000.

Is the Infinity Lean 20K rechargeable?

Yes, over USB-C. The 650mAh battery and the on-screen percentage let you top up before it dies, so the whole 6mL tank is usable.

What nicotine strength is it?

20mg/mL (2%), the maximum allowed in Canada. WAKA Optimus is the alternative at 1.8%.

Which flavours are best?

Watermelon G and Wild Berries for non-iced, Lychee Ice and Blue Razz Lemon Ice for cooling. Extreme Mint is the coldest option.

Which mode should I leave it on?

Smooth, for most people. Switch to Eco when the tank is nearly empty, and use Boost for short sessions where flavour matters more than runtime.

Is it good for heavy vapers?

It works, with a caveat: heavy use on Boost means charging every few days and reaching the weaker end of the tank sooner. If that sounds like your routine, the 30mL tank of a 120K device is the more comfortable fit.