First Defense 360 Inert MK-4 Stream AerosolThe 3 oz. MK 4 canister will deliver 20 25 short bursts of OC at an effective range of 10 12 ft.? The 360 stream delivery method allows the aerosol projector to disperse OC from any angle while providing a target specific, strong concentrated stream for greater standoff. The green canister represents the inert training units which duplicate the delivery system for live products.? The MK 4 is an ideal size for patrol officers to wear on a duty belt.