I’ve used Malkoff devices since circa 2008, hard to believe it has been 10 years already.

Malkoff started by making LED drop-ins for incandescent Surefire lights like Surefire 6P and 9P and stuff. Remove the bezel, remove the stupid incan module that’s dim, high energy consuming and not reliable and insert a M60 drop-in module. That was back in the day. Then he came up with M61 and others. They never burn out, have way lower consumption and better tint IMO. You can get cool, warm, neutral, etc. The pure white ones are the brightest, the ‘warm’ ones are the dimmest but have better color rendition.
I like neutral ones.

Gotta realize Surefire was revolutionary back in the 1980’s, where a tiny torch generated 60 lumens. That was 4 times brighter than a Maglite and you could actually EDC it anywhere. But they were a bit slow accepting the LED revolution, a bit behind the curve and Malkoff brilliantly stepped in.
Surefire invented – well, technically they didn’t, but they were instrumental in adoption of 123 cells.

Take your old 1990’s Surefire 9P, insert a Malkoff – any Malkoff and you have a brand new light. That’s basically as indestructible as it gets.

Have a bunch of Malkoffs, M61, M61L (Low), and Low-Low and most importantly, Malkoff expanded into flashlight making, his Hound Dog series is most impressive – I have 3 of them.
The bigger ones take 4×123 primaries or 2×18650 Li-on and generate over 1000 lumens for 2 hours. That is brilliant. There is also that Wildcat model that’s less throwy but more floody if you like that. It’s truly a wall of light. Then Malkoff makes smaller Surefire 6P type lights, I don’t have one but they are compact and have a lot of fans. I prefer to modify surefire lights with Malkoff modules. I also prefer to get aftermarket 6P bodies that are bored for 18mm. However when looking at huge throwers, Surefire doesn’t really make an equivalent light that can be modified, so the Hound Dog makes a lot of sense.

Malkoff Devices does not build lights to the Surefire standard, IMO he exceeds it and certainly exceeds it in terms of value. If you want the best, it’s all that.

My only non-Malkoff light is a Surefire G2x Pro – it’s advantage is it’s made of nitrolon and it’s very light. I wish Surefire would expand heavily in that direction. It’s feather-weight. My dream Surefire is a light based on G2x Pro but takes 3×123 versus 2×123. Even a 4×123 model would be really interesting. They are light and easy to grip, nitrolon just sticks to one’s hand.

My only criticism of Malkoff is: He needs to make anti-roll heads – like Surefire and the lights could use some heavier knurling. He did come up with a tri-cap that kind of solves the roll problem.

But really, nothing is as reliable as the olde Surefire Z41 twisty tailcap!