The Olight M31 Triton has the same LED and reflector as the SR50, but in a longer, thinner body. Both lights use the Luminus SST-50 LED to put out 800 lumens out the front of the light on high. The M31 has three brightnesses plus strobe, giving you a wide range of available illumination options for just about any situation. The large smooth reflector on it gives some great throw, meaning that you can light up stuff hundreds of yards away when necessary.
The M31 changes modes in the same way as the M20 and M21, by loosening and tightening the head. Each time you do that, it will cycle between the four available modes. It is powered by 3 or 4 CR123 batteries or 2 18650s. If you want a ridiculous amount of light, the M31 is a great choice.
See it in action: