Works on AR15/M4 platforms as well as any other firearms platforms with a Weaver/ Picatinny/ MIL-STD 1913 rail. This riser helps with getting low mounted optics and raising the optic up another 3/4 of an inch to a more comfortable cheek rest and shooting height. The rail has a hollow channel through the length to make it lighter and for some firearms act as a see-through sight channel to use the iron sights.