This ammo is intended for .22 handguns. Aguila .22 Super Colibri is super-quiet ammo that does not contain gunpowder but fires from the force of the primer only. Powerful and silent, great for use in urban areas. This is a 20-grain bullet in a brass case. Will break glass and penetrate hard tin cans. Velocity is 500 fps (11 foot-pounds) at the muzzle and can be lethal. This ammo works great and is intended for .22 handguns only. There are 50 rounds per box, 10 boxes per 500-round brick. We sell this by the 500-round brick. A full case would be 10 bricks or 5,000 rounds. Non-returnable item; we will not accept any returns on this. Do not use in long-barreled guns, as the projectile may become lodged and be dangerous (lethal) if a regular cartridge is shot as a follow up. Will not work the slide in semi-auto handguns.