Streamlight ProTac 2L-X USB Review: The One That Still Works

Who this light is for

Every other light on this site is optimised for something: size, price, output, configurability. The ProTac 2L-X is optimised for working.

Streamlight's business is duty gear — lights that go on belts of people whose evening depends on the thing turning on. That heritage shows up in decisions that look conservative on a spec sheet and sensible in a blackout: a modest output it can actually hold, a programmable switch that lets you delete the modes you don't want, an IPX7 body, and a battery system with a genuine fallback.

If your priority is the biggest number per dollar, this is the wrong light and you'll feel that keenly at the checkout. If your priority is that it works in two years, on a cold night, when you haven't thought about it since spring — this is the answer.

Specifications

Multi-fuel is the entire argument

This is the feature worth buying the light for, and it's the one the spec sheet undersells.

The ProTac 2L-X ships with Streamlight's SL-B26, a rechargeable 18650 with a USB port built into the cell itself. Day to day you use it exactly like any modern rechargeable light. But the body also accepts two CR123A lithium primaries — and CR123As sit on a shelf for around a decade without meaningfully self-discharging.

That combination solves a problem no single-format light can. A rechargeable light is convenient until the power's been out for three days. A primary-only light is dependable but wasteful for daily use. This one is both, and switching between them takes about fifteen seconds.

Keep two CR123A cells taped inside the lid of your emergency kit. That turns this from a flashlight into a flashlight that is definitely going to work, which is a materially different object.

Compare that with the Olight Baton 4, whose sealed cell is its one real weakness, or the ThruNite Archer Mini, which is disposable by design. Both are good lights. Neither is one you'd stake a genuine emergency on.

TEN-TAP: the switch you can edit

Out of the box the tail switch cycles high, strobe, low. Streamlight's TEN-TAP programming lets you change that to high only, or high and low with no strobe, using a defined tapping sequence.

That's a genuinely thoughtful piece of design and it's rare. Most manufacturers decide your mode order for you and bury a strobe where you'll hit it by accident — a complaint we've made about several lights on this site. Being able to simply delete strobe is worth more than most of the features brands advertise.

Set it to high-and-low and you have a two-mode light anyone can operate. That's the right configuration for almost everyone.

About that 500 lumens

Let's be direct: 500 lumens costs about fifteen dollars elsewhere, and you're paying considerably more here.

What you get for the difference is that the 500 is real and sustained rather than a burst figure — an 18650 body with genuine thermal mass holding a modest output does not need to step down hard, which is the same physics our lumens vs. throw guide describes from the other direction. Nearly three hours on high is a long time.

The 6,800 candela and 165 m beam put it in useful middle ground: enough hotspot to identify something down a driveway, enough spill to see your feet. For everyday use that's a better-judged beam than most high-output lights manage.

Still — if raw output is what you want, this is poor value and you should buy accordingly.

Where it falls down

The 40-lumen low is too high, and we're going to be consistent about that. Our buying guide calls a sub-10-lumen mode non-negotiable, and this light does not have one. Forty lumens at 3 a.m. will wake a room and reset your night vision. It's the single biggest thing keeping this from a higher score, and no amount of duty-light pedigree excuses it.

It's a big light. At 5.14 inches and 111 grams it's a jacket, bag, or belt proposition. It will not disappear in jeans, and if that's your constraint you want the Archer Mini or the Baton 4.

The tail switch is a duty-light convention. Excellent for momentary-on in an overhand grip, more awkward one-handed in a normal grip than a side switch.

CR123A primaries are expensive. They're an insurance policy, not a running cost — use the rechargeable day to day and keep the primaries sealed.

Accessories worth adding

• A four-pack of CR123A primaries — the whole point of the multi-fuel design, and useless if you don't own any. CR123A cells on Amazon.
• A spare SL-B26 cell — lets you rotate a charged battery in without waiting. SL-B26 cells on Amazon.
• A belt holster — this is one of the few lights on this site genuinely big enough to justify one. Holsters on Amazon.
• A diffuser — turns the hotspot into lantern light during an outage, which is exactly the scenario this light is built for. Diffusers on Amazon.

What to buy instead

The verdict

This is the light for the glovebox, the emergency kit, the toolbox, and the person who would rather own one dependable thing than three interesting ones. The multi-fuel battery system is a genuine engineering answer to a real problem, and almost nobody else offers it.

It is not the brightest, cheapest, or smallest light here, and the 40-lumen low is a real flaw rather than a quibble. Buy it knowing exactly what you're buying: reliability, at the cost of the numbers.

Frequently asked questions