The flashlight was sent to me by Convoy for review.
Here’s the product’s links (non-affiliate) for more info: ConvoyStore Convoy M21J , AliExpress Convoy M21J
The Convoy M21J comes in a hard cardboard box.
The flashlight is seated inside some laser cut foam for extra protection during shipping.
The Convoy M21J uses 2 x 21700 cells.
It comes with black anodization and as usual per the Convoy standards, the fit and finish is excellent.
Overall the light follows a very clean design.
Along its body and tail we find some grooving to enhance grip.
My own bundle also included two Vapcell F58 cells, rated with 5800mAh of capacity.
Along with the batteries, there’s also a spacer included that allows flat top cells to be able to contact each other.
The M21J is operated via dual switches.
An electronic switch is mounted on the lower part of the head and it’s used to operate the modes of the flashlight.
The switch is covered by a semi translucent boot and is held in place by a polished metal retainer.
The power on/off of the flashlight is operated by the rear mechanical switch.
On the tail of the flashlight, we can see a thick copper spring.
The switch assemebly is secured in place via a brass retainer.
Here’s the tail fully taken apart.
And a closer look at the switch.
The head comes with a polished metal bezel.
Inside the head we find a 50mm 3 degree TIR lens along with a Luminus SBT90.2 emitter.
As with all Convoy flashlights, the head can be easily taken apart.
On the back side of the head, we find the driver, which according to the specs it can deliver up to 20.5A of output current. In order to minimise resistance, a brass tab is used as the positive terminal.
The driver is held in place via another brass retainer.
User Interface
The majority of Convoy flashlights come with very easy to under UIs, and the M21J is no exception.
Here’s all the supported action by the flashlight:
Turn on/off: Single press (rear switch)
Mode cycle: Single press (front switch) (1% > 10% > 35% > 100% > 1% > …)
Strobe: Double press (front switch)
Momentary On: Half press and hold (rear switch)
Mode memory is present for all modes excluding the Strobe.
Output
Here’s my output measurements using the included Vapcell F58 cells.
As we can see, the Convoy M21J pushes almost 4000 lumen OTF at startup while puling 9.78A from the cells connected in series.
Overall, mode spacing looks pretty good.
Outdoor Beamshots
Here’s some outdoor beamshots of the Convoy M21J.
Needless to say, some neighbours were looking strange at me while I was deploying this light cannon 
Final words
I think the pictures speak for themselves.
Build quality is great and the light produces a large, throwy beam with big output.
I would like to mention that the Convoy M21J is a flashlight I’d recommended only towards flashlight enthusiasts.
This is not a light to give to your parents or your kids to play around, as it pulls a significant amount of power and generates plenty of heat.
Additionally the dual cell setup requires proper handling of the batteries - always keep them balanced / equally charged.