Packaging and Contents The SP31 arrived in a basic cardboard box. The light is protected in a bubble-wrap sleeve and there is foam padding on the bottom of the box. Accessories included clip (pre-installed), 2 spare O-rings and manual. This light also includes a Sofirn 18650 battery and USB-powered charger. The packaging is more than sufficient in addition to the mailer packaging. There is no significant risk of damage or scuffing to the light during delivery using this packaging. This packaging is better than I have seen for some other lights (in other lights I've experienced scuffed finishes from poor packaging). It is possible, but unlikely, that the box may come open during transport if it is shipped loosely in a larger box.

1 x Sofirn SP31

1 x Clip (Pre-Installed)

2 x Spare O-ring 1 x Manual

1 x Sofirn 18650 Lithium Battery 1 x USB-Powered Lithium Battery Charger (700mA)















Included battery and charger. The charger is USB powered and requires a standard-sized USB outlet/power source. The side that connects to the charger is micro-USB sized. The charger is rated at 700mA charge current.



Fit and Finish The SP31 has smooth black anodizing (Type III HA). The anodizing was applied well and my copy did not have any notable defects in the finish. The anodizing has a nice non-glossy sheen and I feel that this finish looks very nice and professional in quality (cheaper lights have an overly glossy or painted-on appearance).



The body of the light is a 18650-size EDC tube design that some people also may describe as an "S design". The width is similar to fat marker. It is a little thicker but shorter than a dry erase marker. Due to the design, there is minimal roll-resistance unless the clip is attached.





























The threads were cut perfectly square and a nice touch is the anodizing on both the head and tail threads. Thanks to the smooth anodizing, the threads were buttery straight from the factory. I added my preferred lube, but it was not necessary.









Lanyard and Case The center and tail of the body has a subtle diamond pattern knurling which adds grip, a clean look, and some scratch resistance. The knurling is not overly aggressive and it feels good in hand. This is perfect for use bare-handed.The threads were cut perfectly square and a nice touch is the anodizing on both the head and tail threads. Thanks to the smooth anodizing, the threads were buttery straight from the factory. I added my preferred lube, but it was not necessary. No lanyard or case included. The included clip is great although I would have also liked a lanyard. Fortunately, I already own a few spare lanyards that work perfectly.

Tail Stand









The SP31 can tail-stand on a level surface and is stable. Installing a lanyard will de-stablize tail standing somewhat. User Interface and Modes The light has a rear forward-clicky (On/Off/Momentary) and uses a side-switch to control modes.

Output starts low and cycles up then back down. FF -> L -> M -> H -> M -> L -> FF

There is mode memory. The light will activate on the last used brightness. Strobe & bike strobe are hidden.

Operation:

To turn the light ON (MOMENTARY), partial press and hold tail switch.

To turn the light ON, press tail switch.

To advance modes, press side switch (FF -> L -> M -> H -> M -> L -> FF)

To turn the light OFF, press tail switch. Operation: Strobe / Bike Strobe (Hidden): To turn STROBE ON, double-click side switch (when on).

To turn STROBE OFF, press side switch (will return to previous mode). To turn BIKE STROBE ON, long-press side switch (when on).

To turn BIKE STROBE OFF, press side switch (will return to previous mode).

Comments: I like the mode rotation (which goes up then back down). The side switch UI is very intuitive and I also like that Firefly is not hidden and part of the normal mode rotation. I always like when strobe modes are hidden. Because the mode and power switches are different, it's also very easy for me to always change the mode back to Firefly before turning it off so that it always starts on the lowest mode.









Comments: I like the mode rotation (which goes up then back down). The side switch UI is very intuitive and I also like that Firefly is not hidden and part of the normal mode rotation. I always like when strobe modes are hidden. Because the mode and power switches are different, it's also very easy for me to always change the mode back to Firefly before turning it off so that it always starts on the lowest mode. Output, Runtime and Power





Measurements were done using a freshly charged EVVA protected Panasonic NCR18650B.





I estimate High exceeds spec at roughly 1060 lumens at 30 seconds (I measured 1056 & 1066 on two different runs). Peak at activation was about 1140 lumens. This makes it a 1060 lumen light by ANSI FL 1 standards. Medium is 485 after 30 seconds (initial peak was 486).





Like most 18650 tube lights, I consider the 1060 lumen mode to really be "Turbo" as the light will get very warm on this setting. I consider the 485 lumen mode to be "High" and this mode is best for sustained high-brightness use.

"Firefly" mode was almost exactly 1 lumen (I measured 1.4 lumens). This is my ideal setting for the lowest power level. I consider this to be "perfect".



PWM I did not detect PWM on the SP31 via video method. If it has PWM, it is very high frequency.



Regulation





This light has timed step-downs when on High or Medium. * When on High, the light will step-down to Medium after 3 minutes. * When on Medium, the light will step-down to Low after 30 minutes.

Comments:

* The user can manually step back up the power. * The light does not get that hot on Medium. I suspect that the step-down at 30 minutes is in the interest of saving energy as well as to provide extended run-times since the light can run for a very long time on Low. * On Low, the light is barely warm. * This test was done with a constant cooling fan. Ambient temperature in my house was 78F (25C). * This test was done with a constant cooling fan. Ambient temperature in my house was 78F (25C). * Low and Firefly both have very long runtimes.



Beam Profile

Balanced General Purpose. The SP31 uses a domed Cree XP-L2 V6 3D in a polished reflector. The beam is very balanced for general purpose use with a relatively large hotspot. The hotspot is large and transitions smoothly and gradually throughout the beam. The beam has defined edges. This light works very well for people seeking a more balanced beam. This light works great for general purpose use both indoors and outdoors.



















Beamshots, Color Temperature and Tint























The Sofirn SP31 is a very nice warm neutral white at 4700K. When white-balanced in Adobe Lightroom against "Daylight 5500K", the beamshots appear slightly warm to neutral. The light appears slightly warm white in practice. This is a very good choice of default color temperature and I'm really happy to see a manufacturer using this color temperature for a light.





Low Voltage Protection (LVP) I confirmed that this light has LVP. The light will start flashing about a couple times per second when the voltage is around 2.8-3V and the light will turn off entirely 1 minute after hitting 2.8V.





Battery Support and Fitment The SP31 is powered by 1x18650 lithium-ion (INR, IMR, ICR, etc.) Protected Batteries Fit. The EVVA Protected Panasonic NCR18650B fits fine length-wise at 69.5mm and width-wise at 18.67mm. The included battery is also protected and fits fine. The dual-spring design is very tolerant of a range of battery lengths. Button vs Flat-Top: Both the Panasonic and Sofirn batteries were button-top. Flat-top batteries should also fit due to the dual battery springs.

The positive & negative contacts are both springs. The positive & negative contacts are both springs.















Lock-Out You can physically lock-out the light by loosening the tail (or head) one-half turn to break the circuit. I confirmed that this light has LVP. The light will start flashing about a couple times per second when the voltage is around 2.8-3V and the light will turn off entirely 1 minute after hitting 2.8V.You can physically lock-out the light by loosening the tail (or head) one-half turn to break the circuit.



If there is a possibility of accidental activation, you should lock-out the light.





Size Reference

Flashlight pictured next to a AA, 18650 and C8 for size reference.













