At the end there will be a summary for those who like only particulars. In each topic I will bold the key sentences, so it will be easier to notice what’s the most important. Enjoy!
You can buy it here:
Be sure to use this coupon code I got from Sofirn: SOFIRNSP31
Table of Contents:
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General parameters
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Package content
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Appearance, parameters
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UI, runtime and charging
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PWM
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Waterproofness
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Light pattern, tint
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Summary
| Type | Description |
|---|---|
| Material | Aluminium |
| Color | Black |
| Lens | Plastic TIR, not covered with glass |
| LED | SST40 6500K cool white |
| Switch | Mechanical tactical switch (on/off) + side e-switch (switch modes) |
| Brightness | 2000lm max, theoretical |
| Throw | 269m, 18100cd |
| Power | 20W |
| Modes | 5 + strobe, SOS, beacon |
| Mode memory | Yes |
| Battery | 1x 18650 |
| Overheating protection | Yes, brightness decrease at 55degC |
| Reverse polarity protection | Yes |
| Low voltage protection | Yes (cutoff at 3V) |
| Waterproof | IP68 |
| Impact resistance | 1m |
| Size | [Diameter: (Head: 25mm / Tube: 25mm)] / Length: 122mm |
| Weight | Flashlight: 62g / Flashlight + battery: 107g |
Inside were:
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Flashlight
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Lanyard
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2 spare o-rings
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Manual
SP31V3 is compact, fitting snugly into a front pocket and proving quite convenient overall.
One notable absence is the lack of a steel bezel at the front, which some might consider a downside. Admittedly, steel bezels have their pros and cons, but for the sake of this discussion, let’s consider it a drawback in a “tactical” flashlight.
Sofirn opted for clear TIR optics upfront, but unprotected by a glass lens. This means:
a) It’s resistant to breakage or shattering on impact,
b) It’s prone to scratching easily.
The verdict on whether the absence of glass protection is advantageous or not largely depends on your preferences.
The flashlight features an electronic side switch with a battery power indicator light. The switch offers a satisfyingly soft yet distinct click, and a pleasant dim light.
The rubber USB port cover sits flush with the body and is quite snug.
When opening it, be cautious not to pull it open forcefully like a door; instead, slide it aside gently. It’s secured to the body by a small rubber strap, which may stretch and turn white when opened incorrectly, suggesting it’s prone to snapping. It happened to me with the BLF LT1, but I hope one day Sofirn will devise a sturdier attachment method.
Threads are very well lubricated, rubber o-ring is thick and fits tightly, preventing any water leakage.
Pre-mounted clip is good. It is stiff, hard to open, but will hold onto your pocket securely. It also has a lanyard hole.
There is also a lanyard hole in the tailcap, along with mechanical tactical switch.
And finally, the lanyard. It is okay, really nothing special.
UI
Sofirn ingeniously combined a tail tactical switch for on/off functionality with a side e-switch for mode cycling. This configuration proves optimal for tactical flashlights, making it effortless to operate and switch between modes.
Runtime
I conducted tests on the medium mode (stated as 300lm). The results were rather uneventful, with consistent brightness output throughout the entire test. Notably, towards the end, the brightness diminished to approximately 13lm but maintained that level for several additional hours.
------ Graph will be updated tomorrow. ------
Heat dissipation
Given its compact size and high brightness output, overheating is inevitable. The built-in protection activates at 55°C, reducing brightness accordingly. It’s always a delicate balance; a heavier flashlight may heat up more gradually but risks being too bulky for everyday carry.
Charging
Equipped with a built-in USB type C charging port, the flashlight’s rubber cover effectively seals everything tightly, ensuring waterproofing. My only concern lies in the cover’s attachment. But I covered this topic above.
Very very slightly visible on camera, undetectable to naked eye.
With its IP68 rating, there’s no doubt about its waterproof capabilities. After two hours underwater, there were no signs of leakage, as expected.
Luminus SST40 6500K cool white. Clear TIR optics. Max brightness 2000lm, max throw 269m.
Narrow, “tactical” beam profile.
I created this visualization to better show the beam profile. Black lines are at 90%, 70%, 50% and 30% brightness. The tighter the line, the more rapid and sudden the light dimms.
You can see the line near the center is very tight, because the optic used is clear, so hotspot is tight, but on the edges, the line is wider, which means light spreads more evenly.
Sofirn SP33V3 is a “tactical” flashlight. It means it shoul attract soldiers and middle age divorced men. Is it tactical? The tactical side would be cool white tint, focused beam, dual switch, and…and that’s it. I would say it is more EDC than tactical. Small size, lack of steel bezel - it just looks like an EDC light. And it is pretty good. I like it. It is generally a well designed flashlight, nothing bad about it. I really like the USB charging port - must-have feature in lightweight and simple travelling, for me.
The thing is, if you need a “tactical” flashlight, maybe try to find something else. But if you just need an overall good and well priced ($27 at 21.04.2024) flashlight, this is the one. 
Pros:
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Great UI (tail switch + side e-switch)
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Convenient LED battery indicator
Cons:
- Weak attachment for the USB cover, prone to snapping
If you have any questions, put them below, thanks for sticking for a while