Sofirn ST2 Flashlight
An overview
Sofirn ST2 | Manual
Summary
Long-lasting, easy-to-pack, electric-shaver-shaped work light with a tilting head. SFT42R/6500K in smooth reflector: ~2600 lm / ~300 ANSI m max for 1 min (~650 lm sustained for 5 h) + red/UV. Beam Acuity Index of ~5. 2*18650 replaceable batteries, USB-C charging, a button with smooth-ramping UI, and a dial to select the LED (white, red, UV).
Specs (white)
Min: ~5 lm
Max: ~2600 lm for 1 min
Max sustained: ~650 lm for 5 h
Light content: >3000 lm×h
Useful Reach: ~150 m (300 m ANSI)
Beam Acuity Index: ~5
Light quality: ~6000-6500 K, lowish CRI, slightly greenish tint
Physical
Despite its almost 250 g heft, the light's shape makes is easy to hold, pocket or stow. There is a clip and a tail magnet. Tilting head (90°) is surprisingly helpful in all use scenarios, including hand-holding and ceiling/wall-bouncing while tail-standing without self-blinding.
Light
In addition to the white SFT42R 6500 K LED, there is a red LED (allegedly SST20 640-670 nm peak) and a UV LED (SST08UV-H 365 nm peak). Each emitter sits in its own small smooth reflector.
White
The beam has a smooth transition form the hotspot to wide spill, reminiscent of TIR. The light is of lowish CRI and has some greenish tint (but only in comparison to other lights). The Min (moon) is on the brighter side (~5 lm) and the Max is around 2600 lm for 1 min. It holds ~650 lm (some 25% of Max) for ~5 hours. The ANSI nominal throw at max is about 300 m (~150 m of Useful Reach).
On Max, the light steps down to ~25% of Max output on a timer after 1 min. In addition, there is a thermal step-down regardless of timing. The head gets warm on Max, but the flashlight body - separated by head hinges - much less so. The stepped-down levels are regulated by buck driver (according to Sofirn).
On Max the output current is some 10 A or 35 W.
Red
The red LED has a smooth ramping (first time I saw it) and a blinking mode. The beam is spotty.
U/V
The UV LED has no filter and emits visibly bluish glow whose reflections interfere with fluorescence. There are two intensity levels. Compared to Sofirn IF16 UV with ZWB2 filter, the hotspot is larger but still throwy, with similar intensity at max - the filter makes all the difference - you need it with this wide-spectrum UV LED.
Runtime
On Max (white), the light steps down from some 2600 lm to about 650 lm after 1 min, then holds steady at this level for about 5 hours. There is a ~30 min reserve at some 300 lm at the end.
Batteries and Charging
Two 18650 (nominally 3800 mAh each) replaceable batteries in parallel: 4.21 V charged, 2.97 V empty. Charging via USB-C at 2 A takes some 5 hours. Light is usable while charging. There is no reverse-charging/power bank functionality. There is a 4-level battery voltage indicator for 5 s on turn-on.
Controls
There is a button with a 3-position dial around it. The dial switches between white, red, and UV LEDs. There is smooth-ramping for white and red (it takes 4 seconds to go from Min to Max or vice versa) and two-level toggle for UV. The ramp seems a little to fast at low end but passable overall. The last level is memorised for white, red, and UV separately. The last-level memory can not be turned off. There are shortcuts to Min and Max as well as to white strobe (SOS, beacon) and blinking red. Four clicks from off locks and unlocks the button.
Usefulness
The light is handy. Easy to use, easy to store. Extra red/UV emitters give it more breadth. The throw is respectable and the beam pleasant and useful. Tilting head is helpful.
But the highlight is the amount of juice that such a pocketable package can hold: more than 3000 lm×h. That's about 10 times as much illumination as one can squeeze from the likes of HD12 or T6! It is may be quite a rational choice for 'the flashlight' to have.
A far shot, but the ST2 also reminds me of the once-popular flat 4.5 V battery lights that I grew up with and found very useful at the time. Nostalgia is not what it used to be...
Acknowlegments
Sofirn has provided the flashlight for testing free of charge. Thank you!
Other reviews, videos, and opinions
February 2026 
