When Speras presented the light on BLF, I found the concept quite interesting. As a dog owner, I like small lights anyway – they are perfect for walking the dog around the block at night. However, being able to swap the 18350 tube for a 21700 one is something I hadn’t come across before. I wanted to test for myself how well this works and whether these cells – which are quite different in capacity and discharge capability – actually play nice together in one flashlight. Speras gave me the opportunity quickly and unbureaucratically - thanks a lot for that!
All my reviews can be found on my website.
Review of the Speras M4 v3 on dahamstah.de
Disclaimer: Speras provided this light to me free of charge. This had no influence on the review.
The M4 v3 is only available in one version - matte black, as shown here. As accessories, there is the 21700 battery tube shown here and the matching 21700 cell.
The light arrives in a small white box with yellow accents. All important specs of the light are printed on it. The M4 v3 itself sits securely in a plastic tray. The battery is pre-installed and protected by an isolation disc. The box allows a view of the light. The 21700 tube was included in a small white box, and the extra 21700 battery – a Speras S50 – was packed right into the flashlight box and marked with a sticker on the packaging. Also included are two spare O-rings, a lanyard, a USB-A to USB-C cable, and a manual.
My first impression of the light was very good. The black anodization has a satin finish and feels high quality. There are no sharp edges and no flaws in the anodization at all. The threads are anodized, allowing physical lockout by slightly loosening the tube. Only the thread connecting to the tailcap on the 21700 tube is bare.
By the way, there is only a tailcap on the 21700 tube. The 18350 tube is a one-piece design. The short tube features fine, angled knurling and sits very nicely in the hand. The long tube has larger, smooth surfaces separated by grooves and raised ridges. It feels a bit slicker, but not to an extent where it becomes uncomfortable.
On the head, located in the cooling fin area, sits the switch. It’s easy to find, rubberized, textured, and equipped with a battery indicator. The rubber boot protrudes slightly from the flashlight body and is surrounded by a smoother, glossier ring. The battery indicator is four-stage and sufficiently bright. It’s easy to read during the day and doesn’t blind you at night.
Opposite sits the USB-C port. It is closed very securely with a rubber plug and should be fully waterproof. The cutout is large enough that you shouldn’t have any issues even with thick cable plugs.
The bezel is also made of aluminum and anodized black, with all the markings laser-etched onto it. The lettering is cleanly done and kept refreshingly minimal. It’s a nice touch that the logos align pretty accurately with the switch and USB port. The bezel is not glued, so modding shouldn’t be an issue.
At the heart of the light sits a cold white Luminus SFT-42R, hidden under a TIR optic. It looks like there is an AR-coated glass lens over it, but since I didn’t disassemble the light, I can’t say for sure.
The walls of the 18350 tube are fairly thick to make up for the diameter difference relative to the head. While this adds a bit more weight than strictly necessary, it makes the light feel extremely solid and premium. For my hands, the extra thickness actually improves ergonomics. The light feels great in my hand with both tubes, though I actually like the long tube even better than the short one.
With both tubes, the battery is spring-loaded on both ends, guaranteeing good contact. You can also get a glance at a few components on the driver.
Imalent BTL50, Wurkkos TS28, Speras M4 v3, Wurkkos TS11 , Acebeam K1
| Dimensions | head dia. | tail dia. | length | weight |
|---|---|---|---|---|
| 18350 | 40mm | 25,5mm | 85,5mm | 115g |
| 21700 | 40mm | 28mm | 119mm | 166g |
Lanyard: A lanyard is included. It has a comfortable, flat strap and feels sufficiently dimensioned for the light while staying relatively slim and lightweight. It attaches to a lanyard hole in the tailcap. The hole is side-mounted, so both tailstanding and the magnet still work perfectly.
Clip: A pocket clip is not included. On the 18350 version, a clip wouldn’t do much anyway, but on the 21700 version, I could definitely see it working well.
Magnet: There is a magnet in both tubes. These hold the light securely in any orientation, even on smooth surfaces without slipping.
(Jacket)pocket: Jacket pockets are absolute home turf for this light! It tucks away nicely in either configuration. The head is a bit too thick for pants pockets - it works if your pants aren’t too tight, but it’s not ideal.
Explanation 1C, 1H...
1C: short click, 2C: double click, …
1H: press and hold without letting go
2H: short click, followed by 1H
The UI is pleasently simple, yet includes all the essential features. It follows the standard shortcut layout in the flashlight world, so there are no surprises. For a light with a side switch and a single LED, this works perfectly in my eyes – there’s a reason it has become the standard.
| State of the light | Action | Result |
|---|---|---|
| off | 1C | on, memory |
| off | 1H | on, lowest level |
| on / off | 2C | Turbo |
| on / off | 3C | Strobe → SOS |
| off | 4C | lock / unlock |
| on | 1C | off |
| on | 1H | Change brightness level |
All measurements were done in my 30cm integrating sphere. The temperature was between 20 and 24°C. Additionally, an Opple Light Master III and a TASi TA636B lux meter were used. Please note that this is hobby equipment, so inaccuracies and deviations are possible!
The light is clearly a thrower. The beam profile is dominated by a sharply defined spot, surrounded by a faint but wide spill. Naturally, a small TIR won’t get you the range of a large-bezel thrower, but at medium distances around 200-300m, the light is in its element, and beyond that still usable.
Especially with the 21700 cell, but also with the 18350, the output on Turbo is quite impressive. Considering this is a relatively small light, I also find the sustained output completely fine. The 18350 cell logically caps performance a bit - but it should be clear that you have to make a few compromises with a small light.
All runtimes except Moon
Without 21700 low
What I don’t like is that the light doesn’t shut off completely. Instead, it ramps down to 1-2 lumens and keeps running. At that level, the current draw is so low that it might bypass the battery’s protection circuit - the light itself lacks LVP (low voltage protection). You should definitely take the manual’s warning seriously to swap the battery as soon as the switch light flashes red! If you hold the light in your hand, you’ll do that anyway because you’re left with very little emergency light. This only becomes critical if you leave the light running unattended, such as during runtime testing.
Turbo 18350 vs 21700
The light seems to run FET/unregulated, but at a solid level. Cooling does not increase performance. The included 21700 cell performs well. Switching to a tabless cell doesn’t yield higher output. It’s a similar story with the 18350 cell, though a 10A cell gives about 100 extra lumens initially - but really only right at the turn-on peak, not even for a full second. You can safely ignore that.
perceived mode spacing
The approximate perceived mode distribution is not an exact figure, but meant to illustrate how the output steps are spaced. The jump from Medium to High is slightly larger than the other intervals - you can see this when cycling through modes, but it’s not bothersome.
Below is an overview of the modes, their respective measured values, and my throw measurements:
| Max. Lumen | Lumen @ 30s | max. temperature | Temp. @ 30s | ANSI FL1 runtimes | |
|---|---|---|---|---|---|
| Speras M4 V3 21700 Turbo | 2589 lm | 2323 lm | 60.3 °C | 45.3 °C | 3h 25min |
| Speras M4 V3 18350 Turbo | 1849 lm | 1620 lm | 46.7 °C | 35.3 °C | 1h 15min |
| Speras M4 V3 21700 high | 1619 lm | 1531 lm | 49.5 °C | 32.3 °C | 3h 39min |
| Speras M4 V3 18350 high | 1231 lm | 1099 lm | 25.1 °C | 24.0 °C | 1h 21min |
| Speras M4 V3 21700 mid | 410 lm | 406 lm | 47.6 °C | 27.4 °C | 4h 14min |
| Speras M4 V3 18350 mid | 386 lm | 379 lm | 40.9 °C | 30.8 °C | 1h 39min |
| Speras M4 V3 21700 low | 177 lm | 176 lm | 30.5 °C | 24.5 °C | 20h 1min |
| Speras M4 V3 18350 low | 170 lm | 168 lm | 31.1 °C | 25.9 °C | 5h 5min |
| distance | at turn on / 30s with 21700 | at turn on / 30s with 18350 |
|---|---|---|
| cd | 187.680 / 176.480 | 145.440 / 128.800 |
| ANSI FL1 | 866 / 840 | 763 / 718 |
| low | Turbo | |
|---|---|---|
| CCT | 5950 | 6100 |
| CRI | 68 | 69 |
| DUV | 0,004 | 0,002 |
Flicker is always in the green zone, PWM is not detectable with the eye or camera.
All measurement results can be found here
For comparison, I selected a mix of lights with TIR optics, lights with SFT42R emitters, and lights with a somewhat similar beam profile. The most direct competitor is likely the Wurkkos TS11. Since the outdoor beamshots only feature images of the 18650 configuration, I’d like to show you both lights side-by-side in their short setup in a single photo. I think you can see pretty clearly that the M4 v3 comes out quite a bit ahead.
Wurkkos TS11, Speras M3 v4
The charge curves look clean for both the 18350 and 21700. Nothing to complain about regarding the CC-CV charging profile. However, 2A is quite high for the small 18350 cell. So I did some research - and there are indeed cells rated for charge currents up to 2A. For the 21700, the charge rate is appropriate anyway.
Since Speras explicitly advertises fast charging, I assume the included cell is rated accordingly. If you want maximum cycle life out of the cell, you should probably stick to charging at 0.5 - 1A in an external charger.
As far as I can tell, all protection mechanisms are handled by the battery PCB. The stepdown behavior of the light isn’t ideal for this though. I suspect the tiny current draw after the stepdown undermines the protection circuit - in my testing, the worst case saw the cell reading at 2.5V after removal. I didn’t want to discharge it any lower for safety reasons. As mentioned earlier, you should swap or charge the cell as soon as the red indicator starts flashing.
The 18350 battery is rated at 1100mAh capacity, my Vapcell S4+ measured 1260mAh. For the 5000mAh 21700 cell, 5048mAh was displayed.
There is no powerbank feature, though that wouldn’t make much sense on an 18350 light anyway.
The M4 v3 grew on me right from the start. Simple UI, good output, great hand feel, awesome form factor.
Whether the driver regulation (which doesn’t squeeze out every last bit of sustained performance) is a drawback or suitable for an EDC light like this is up to personal preference - for my use cases, it doesn’t bother me. The missing low-voltage protection is rarely a real-world problem because anyone will recharge the light once the output drops to almost nothing, but it’s still worth mentioning. Ultimately, it might even be a bonus - in an emergency, I’d rather have 2 lumens for a long time at the cost of a ruined battery than no light at all.
What I really liked is the switch. With its crisp tactile response and nice texture, operation is a pleasure. With the short tube, the light becomes truly compact, with the long tube, ergonomics are great while remaining relatively lightweight. The ability to switch between 18350 and 21700 is a unique feature I haven’t seen done this way before.
The build quality is beyond reproach as well. Not only is the machining flawless, but the light also feels extremely tough. And even though it’s just a small black flashlight, I like the design - especially with the 21700 tube.
If you’re looking for a handy thrower with the option for a high-capacity cell, I can definitely recommend this light - I’d suggest ordering the 21700 tube right along with it, as it really completes the package. Taking a look at the Speras website is well worth it!
