The M203 Grenade Plug (10 piece) are designed to work specifically with the M203 Paintball Grenade .68 Caliber Pro grenades. They are the ideal plug for players who are concerned about their paintballs or BBs falling out of the grenade as they play. Simply load your ammunition of choice into the grenade, plug the top with a M203 Grenade Plug and fire when ready! The M203 Grenade Plugs are made out of soft rubber and are safe to fire, so there is no need to remove them before firing.