Review - Sofirn SP31

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Firelight2's picture
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Review - Sofirn SP31

This is my review of the Sofirn SP31.

This light was provided to me by Sofirn for review. There are quite a few reviews of this light already on BLF. Sofirn has been very generous in sending out review copies.

The Basics:
The SP31 is a tube-shaped 1×18650 light. It has a forward clicky in the tailcap and an e-switch in the head for switching modes. I own two other lights in the same general format, pictured below:
Left to right: Sofirn SP31, Phoenix PD35 Tac, Zanflare F1.

Though none of these lights would qualify as a small 18650 tube light, the SP31 is the smallest of my 3 tailswitch clicky lights with side e-switches.

Build Quality – I EDC’d the SP31 for a week before doing this review. The overall build quality of this light is outstanding. For a light that is listed on Amazon for $30, the build quality is amazing. It looks and feels every bit as good, if not better, than my considerably more expensive Fenix PD35 Tac.

  • Anodizing – The anodizing is a perfectly even and defect-free matte black. It’s every bit as good as the anodizing on any light I’ve seen. The manual lists the anodizing as HAIII and this seems accurate. After EDCing the SP31 loose in my pocket for a week with my keys the anodizing is still in perfect condition with no scratches.
  • LED – this is my first light with an XPL2 emitter. The manual claims 4700-5000K 3D tint, and this seems accurate. Beam quality and beam pattern are excellent. Tint is perfect with no green. The tint looks noticeably better than that on my neutral white Zanflare F1 or cool white Fenix PD35. The rated 960 lumen output seems accurate as the light is quite bright for a single 3.7v emitter. I do not have the ability to measure output directly, but other reviewers have measured peak output on a fresh cell at over 1000 lumens, which is above the rated output.
  • Reflector – interestingly the manual claims “orange peel reflector”. However, the lens in my SP31 appears to be smooth with no visible orange peel. I don’t see any rings in the beam, so this isn’t an issue.
  • Lens – the manual claims the SP31 has an “AR coated lens”. However, I’m not so sure. I don’t see any of the telltale tinted reflections AR coating normally gives when looking at the lens at an angle. And when the light is on, the lens lights up noticeably brighter than the AR coated lens on my Zanflare F1. If the lens is AR coated, I couldn’t see any sign of it. I suspect the lens might not be AR coated. However, this isn’t necessarily a bad thing as the slight gain in output from AR coating is sometimes negated by worse tint and increased chance of damage to the lens.

Hand-feel – Whenever I look at a light, I always like to consider how good it feels in the hand. How easy is it to reach the controls. How do the controls feel in the hand. How secure does the light feel in the hand. I call this “hand-feel”.

  • The hand-feel of the SP31 is excellent. The matte anodizing feels good and the knurling is fairly grippy, but not sharp. The knurling feels about the same as that on a BLF A6. The relatively long tube shape provides plenty of surface area for gripping and the extra knurling on the tailcap helps too.
  • The forward clicky is easy to depress when operating the light and feels much like the clicky on most tube lights.
  • The metal side switch appears to be made of stainless steel. It looks and feels quite elegant. In my opinion it looks better than the metal sideswitches on my Fenix PD35 Tac or Zanflare F1. However, the SP31’s sideswitch is fairly small and only projects up above the edges of the head about 1 mm. It is slightly harder to find by feel than the switches on the Fenix or Zanflare which are larger and project upwards more.

Interface – The SP31’s interface is quite simple.

  • Forward clicky at the rear for on-off and momentary activation.
  • While on, a quick click of the sideswitch to change modes. There are 4 brightness modes including moonlight. Per the manual the light is designed to stay at turbo for 3 minutes and at high for 30 minutes, after which it drops to medium. When clicking modes the light will start in ascending order until it reaches turbo then switch to descending order. The light will remember the last used mode when powered off.
  • Mode spacing – moonlight is nice, but some of the higher modes might be a bit closer together in output than some would like. Having a true non-moonlight low mode would be nice.
  • While on, click and hold for bicycle strobe. This is an usual mode consisting of high interspersed with flashes to turbo. I could see how this might be helpful for bicyclists who want the extra visibility to others provided by a strobe, without the dark periods when the LED is off.
  • While on, double-click for strobe. This strobe mode is also unusual in that it is a non-linear strobe. It starts with a slower strobe and then switches to a fast strobe after a few seconds then switches back to slow.
  • One disadvantage of this interface is there are no shortcuts to moonlight and turbo. The only way to get to those modes is to cycle them one at a time. If you aren’t sure you’re at turbo, you might end up pressing one too many times and have to start over. Depending on how you use the light this could be a significant drawback. For example, if you left the light in turbo and wake up in the middle of the night and want moonlight, your only option will be to turn the light on in turbo then manually cycle modes downward.

Modability – for a flashaholic, it’s always nice to know what, if anything can be modded on a light. How it can be customized or improved.

  • The SP31 comes in 3 parts: head, body tube and tailcap.
  • The threads on the SP31 are compatible with the threads on the Convoy S2+ and Jaxman E2L. This means that tubes designed for those lights will screw into the SP31. However, note that the distance to the driver and switch is different from those lights. You can fairly easily use one of those tubes in the SP31, but you’ll likely need to mod the tube by filing some threads off near the head and adding a shim at the tailcap.
  • The driver appears to be 17mm and is held in place with a brass driver retaining ring. I have not attempt to remove the driver, so cannot be sure of the internal structure, but it’s probably pretty straightforward.
  • The head of the light does not come off by turning it in the hand. It may be threadlocked. I have not yet attempted to remove it using tools.
  • The light has a few shallow heatsink fins on the head. These are shallow enough however that I’m not sure this would be the best choice of host for a hot-rodded ultra-high output light.

Here is a picture of my SP31 using a modded Jaxman E2L 18350 tube (filed a couple mm of threads off near the head, added a strip of aluminum bent into a “C” shape in the tailcap, with the light running on an 18350 battery. In this setup, the light looks and feels like it came with this tube. Though far more pocketable than before, you can see this isn’t the most efficient light as the light is rather big compared to the tiny 18350 battery.

Pros and Cons of the SP31:


  • Excellent hand-feel
  • Good output and excellent tint
  • Good price
  • Stable Tailstanding
  • Superb build quality
  • Simple to use interface
  • Elegant design
  • Threads are compatible with Convoy S2+ opening up modding opportunities.


  • Larger than some 18650 tube lights. For pocket EDC a Jaxman E2L or DQG Tiny 18650 are much more comfortable. This is more a drawback of this format than any fault of the light itself.
  • Interface lacks shortcuts to moonlight and turbo.
  • Heatsink fins are relative shallow limiting hot-rod modding options.
  • Mode spacing could be better.

My overall impression

RECOMMENDED – In the 2-button 18650 tube light format I really like this light. Build quality is excellent and the price is right. It has great handfeel, output and tint and tailstands. Compared to my other 2 simlar looking lights, I like the SP31 better than the PD35 (the Fenix can’t tailstand and has uglier cool-white output). I also like it better than the Zanflare F1 (which I find just a bit too big for EDC). Thumbs Up

Edited by: Firelight2 on 06/26/2017 - 16:12
virencelights's picture
Last seen: 22 hours 32 min ago
Joined: 12/23/2012 - 19:53
Posts: 1269
Location: Knightsbridge, London, UK

is this a 2.7 or 2.5 max amp?
E21A mod and has to be 2.5A max if thats correct.

Virence Custom Built; ArmyTek Viking Pro E21A 6500k 9080 Quadtrix, Jetbeam AAA 9080 E21A 9080 5700k, Jetbeam AAA Nichia HCRI Red Led.