Tokyo Marui M320A1 Spare Cartridge
It comes with one grenade holding 18 BBs, 3 in each groove. Underneath, there is a whole where the gas can flow through to expel the BBs into the distance! Since it is a Tokyo Marui product, it isn't too powerful. If you use green gas, it'll reach distances of a little more than 25 meters with a spread of a couple of a meter or so. If there is a group of people you wish to overwhelm, this will overpower them all in one shot.