These muzzle devices are designed and manufactured by Retro Rifles specifically to pass the "Pinky test" in states such as New York, New Jersey, California, Etc.
3 Prong - Fake slots on side as they do not go all the way through; turning the original 3 prong flash hider into a muzzle extender only. Available in Black or unfinished steel.
A1 Birdcage - Turns the function of the M16A1 flash suppressor into a muzzle brake instead by closing off the front end. Slots on side go all the way through and are function.
A1 Birdcage - Slots on sides do not go all the way through, making this just a muzzle extender. M16A1 Birdcage style.
A2 Birdcage.. Looks like the standard M16A2 / M4 flash hider used today, but has a closed end making this more a muzzle brake instead. Slots on the side are still functional. (one of our favorite muzzle devices for all modern rifle builds)