Convoy M21F

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Convoy M21F review

Convoy M21F specifications

Brand/modelConvoy M21F
Max. LumensNot stated
Max. Beam intensity / distanceNot stated
Battery config.1*21700
Onboard chargingUSB-C
Modes5 + ramping + tactical
WaterproofNot stated
Review dateMay 2022


Today I’m looking at the latest in the M21 series from Convoy, the M21F. The M21 series continues to become increasingly complex, with M21A through M21F available – each having different reflector sizes, button configurations, and options for emitters.

Thankfully Reddit user u/TacGriz (our own Angus) has made an easy-to-understand image that briefly showcases the differences.

This is my first light with an SFT-40 emitter – while I’ve used a dedomed SST-40 before, it’s always nice to have things work out of the box instead of cracking things open.


Package quality.

The M21F comes as a lot of Convoy lights do – wrapped in bubble wrap, inside a white cardboard box – and that’s about it! Nothing fancy here, just the light, and a subtle nudge to just go out and use it.

Total contents:

  • The Convoy M21F
    • Attached, a lanyard

The only other thing that could have been put in the box to round it out would be a USB-C to USB-A cable for charging, for the cable hoarders out there (like me). Other than that, provide your own 21700, and you’re ready to roll.

Flashlight in use

There’s a great feel to the M21F – it’s weighted very well, and isn’t heavy towards the head. This makes it a lot more comfortable when carrying for longer periods. It’s textured to the touch; not overly smooth, and not overly rough – just right.

All functions are done via an e-switch on the side with a shiny blue metal ring around it, and there’s a definite click to it, both in feel and sound. As a result, there’s good feedback when it’s activated.

This light will roll fairly freely if put down though, so it’s best to be aware and secure it in place.

You can tail-stand this light, which comes in handy for bouncing the light off a ceiling, or for taking photos of columns of light outdoors, if you’re into that kind of thing.

The lanyard that’s included is one of the standard-fare lanyards included with a lot of Convoy lights. They’re not particularly high-quality, but they’ll get the job done. I don’t tend to use lanyards with lights though, so it’s somewhat of a moot point.

This is definitely a light that’s good for a night time walk, walking the dog, or similar – due to the small head diameter, it’s not a huge thrower, but it still gives off plenty of light.

Build Quality, and Warranty

The M21F comes with a lovely slate blue anodisation in a satin finish, with a bright blue bezel around the button. There’s some nice heat-sinking fins round where the emitter lies, and even after running it on the highest mode for a few minutes, it’s hot to the touch, but not unbearable.

The knurling on the body tube is more grippy than it appears; with the lined ridges, I had assumed that it would be fairly smooth, but it grabs quite well. It’s quite reminiscent of the texture on Klarus lights, and that works nicely.

There’s an interestingly-knurled tailcap for removing the cell; because it’s angled, my thumb slips a little when untwisting the tailcap, but not much.

Out of the box, there’s decent lubrication on the square-cut threads, and it’s a very smooth feeling to tighten and loosen it.

There’s no warranty explicitly mentioned on the item page, but contacting Simon at the Convoy store is the best idea in the event of mishap, as he’s very responsive. He’ll work out how to make things right.

LED, Lens, Bezel, Beam, and Reflector

The emitter options available with the M21F are the SFT-40, CULPM1.TG, XHP70.2, and the GT FC40. The M21F in my hands is the version with the Luminus SFT-40, a dedomed-from-factory 5050 3V emitter, and is only available in cool white.

This particular emitter is rated at 6500K, and while I’d like to see Luminus get things moving on warmer colour temperatures, I do recognise that outside the niche enthusiast community, most people are happy with cool white. Down low, there’s quite a lot of green visible, but as the brightness goes up, it fades to just straight white.

As expected, we’re looking at cool white, and a positive duv – though that decreases as brightness goes up. 

Very interestingly, the jump from Mode 3 to Mode 4 sends the CCT upwards quite a lot – there’s a rise all through the modes, with Mode 1 being just over 6000K, and hitting ~7500K at the highest!

This seemed a bit odd, so I re-ran the spectro tests a few times at different times of day and ambient lighting, and got results very similar – so I can only imagine that it’s either correct or a particular glitch in my measurement tool.

That said, all of that is tucked below a smooth reflector, giving the light good throw given the reflector’s comparatively smaller size.

There’s a decent size hotspot, plenty of spill – very usable for something like going for a walk as the spill provides plenty of usable light for looking around.

On the top is a crenulated bezel, which appears to be stainless steel. While it’s not technically a strike bezel, it would definitely hurt if you were hit with it.

Dimensions and size comparison

  • Length: 143.8 mm / 5.66 inches
  • Head diameter: 40 mm / 1.57 inches
  • Body diameter: 27.5 mm / 1.08 inches


  • Without cells: 145 grams / 5.11 oz.
  • With Samsung 40T: 212 grams / 7.48 oz.

Compared to competition

From left to right:

Pic 1: Convoy C8+, Convoy M21F, Lumintop GT Mini

Pic 2: Convoy M21F, Emisar D1

Driver & User Interface:

The UI for the M21F is very similar to the Convoy L8 recently reviewed, with one small exception – the M21F has a shortcut to Moonlight (0.2% output, vs Mode 1 which is 1%), which gives the light a little more versatility for carrying more regularly.

A note though – you can’t rotate out of moonlight mode into the regular cycle, which means there’s no shortcut to “low” that lets you keep moving through the modes. A bit annoying.

From OFF:

  • Hold: Turn on to Moonlight mode (0.2%).
  • Single-click:  Turn on to memorised level.
  • Double click: Turbo (100%) mode.
  • 3 clicks: Strobe
  • 4 clicks: Tactical mode (100% when held). Click four times again or disconnect the battery to disable.
  • 5 clicks: Voltage readout.
  • 6 clicks: Change between ramping and stepped mode.
  • 10 clicks: Lockout.

From ON:

  • Press and Hold: Ramp up or down, or step upwards through the modes (1, 10, 40, and 100%).
  • 1 click:  Turn off.
  • Double click: Turbo (100%) mode.
  • 3 clicks: Strobe.
  • 5 clicks: Voltage readout.
  • 6 clicks: Change between ramping and stepped mode

Mode memory:

  • In both ramp and stepped mode, the M21F has mode memory.


  • To moon: Hold from off
  • To Turbo: 2 clicks from anywhere 
  • To Strobe: 3 clicks from anywhere

Low voltage warning:

  • The indicator LED behind the switch will flash red when the battery voltage drops under 3V.


  • Strobe is activated by clicking three times.

Lock-out mode: 

  • Activate lockout mode by clicking 10 times from off, or slightly unscrewing the tailcap.


  • No PWM visible to my eye.

Batteries & Charging

The M21F takes 21700 cells, and I have been testing it with the Samsung 40T. There’s nothing specifically mentioned about protected cells, but taking a look at how the 40T sits in the light, I’d be hesitant of putting a protected cell in due to concern of it crushing it a little.

Charging is onboard via USB-C, and can be done via USB-A to C cable, or C-C. No cable is included, so it’s up to you to decide how to charge it.

Charging rates:

USB-A to USB-C: 4.96V @ 1.88A (9.33W)

USB-C to USB-C: 5.05V @ 1.89A (9.56W)

Performance test

For my readings, I use the following:

Lux Meter: For lumen readings and runtimes, an Adafruit TSL2591 connected to a Raspberry Pi running Ubuntu, using RuTiTe by bmengineer in a custom sphere. A UNI-T UT383S is used for candela readings.

DMM: UNI-T UT139C and UNI-T UT210E – 16AWG wire is used directly into the 139C via some banana plugs, and 8AWG wire in a loop for the UNI-T. The DMM I use depends on how high the expected current will be – I use the 139C for <10A, and the 210E for >10A.

Lumen measurements (for each mode)

Output of the M21F was tested with a Samsung 40T in stepped mode. After each test, I left the light to cool (particularly for the higher modes) while recharging the cell via USB to ensure consistency.

ModeAmps at startSpecsturn on30 sec10 min
Moon46.9mA1 lm
Mode 173.3mA25 lm
Mode 2263mA291288 lm281 lm
Mode 32.27A802 lm767 lm720 lm
Mode 47.29A1902 lm1755 lm759 lm

Parasitic drain:

  • 28µA

Runtime graph

There’s some very nice regulation here – while there’s the expected hard drop from mode 4, and a slight drop down in mode 3, after those drops it’s a nice steady output for the expected run, and then on all modes, a final drop to around 25 lumens.

On the runs I did, I stopped the runtime after around 10 minutes at that level, as I expected it to run for quite a long time at that output. This still shows the “main” output though.

Throw numbers: 

I tested modes 1 and 2 at 5m, and modes 3 and 4 at 10m to account for their greater output.

These readings are taken at 30 seconds, to give a good feel of how the light will settle in (ie. worst-case scenario after turning it on for a quick look around).

ModeSpecsCandela measuredDistance in MetersYards
Mode 1N/A1,525 cd7885
Mode 2N/A18,750 cd274300
Mode 3N/A51,500 cd454496
Mode 4N/A125,300 cd708744


Shots taken pointing at the light pole in the distance (around 150m).

Disclaimer: This flashlight was sent to me for review at no cost by Convoy. I have not been paid to review, nor have I been holding back on problems or defects.

Final Verdict


  1. Great throw for the compact head size
  2. Nice easy user interface
  3. Easy to fit in a jacket pocket or similar


  1. Cool white (but the SFT-40 only comes in cool white)
  2. No shortcut to low

Explanation on star ratings:

1: Avoid: my phone flashlight would be a better choice – 2: Poor: significant defect or issues; almost unusable – 3: Average: some defects or issues; but still usable 4: Good: recommended (minor issues) – 5: Great: highly recommended

Reviewer Owen
Author: Owen

4.5 stars: ★★★★⋆

After playing around with this for longer than I usually do for a review, I’ve gotten a good feel for its utility and heft. I really like it; the form factor is very nice, USB-C charging is great to have, I love the slate blue colour.

The only things I didn’t like were that the SFT40 is so “cool”, and that you can’t rotate out of moonlight mode to the normal cycle. It’s not the end of the world, but it’s a little irritating.

Even still – the price point of this light is fantastic, at just over $30USD. 

With that in mind, this light is a solid 4.5 stars – some minor issues overshadowed (pun not intended) by fantastic performance and great bang for buck.

Convoy M21F For Sale

1lumen selects and reviews products personally. We may earn affiliate commissions through our links, which help support our testing.