These with gas or CO2 and BBs filled grenades are used with special launchers (see category grenade launcher). As the trigger is pulled the gas is released and the BBs are blown out of the barrel. The higher the capacity of the shell the greater the surface that can be covered with a shot.
Small and medium sized launchers are mounted on a primary weapon or used individually. Larger models, such as RPG or M72 Grenade Launcher, are often used with CO2 paintball grenades. As the name implies, these 40mm grenades take paintballs which can be very helpful depending on the game scenario and vehicles used.
Grenades are delivered without gas which must be purchased separately. In the category Gas & CO2 it is described which product should be used for the weapon and the product details shed light on whether the grenade is compatible with CO2.