US-made Halbek device. They are based off the original Halbek device, which was made in Rhodesia back in the late 70ies. It reduces the muzzle climb and recoil felt.
 
Specs:
 
1:1 copy of the original Halbek device.
made out of steel
coated in grey
will fit FAL rifles that do not have a 16" bipod-cut barrel
Made in the US