The Legacy Manufacturing Flexzilla Pro 5-pc 3/8" NPT Heavy Duty Safety Coupler and Plug Kit, No. A55656FZ, features ZVR Technology (Zero Valve Restriction) which provides an air tool the maximum cfm possible. Paired with quick, safe, and easy connections, Flexzilla Pro Heavy Duty Couplers and Plugs allow the air tool to operate at its maximum performance. The safety coupler connects and disconnects under zero pressure. Once connected, simply push the sleeve up to open the valve and engage airflow. To remove, pull the sleeve down to shut off airflow and pull the top collar down to disengage the plug. The kit includes an FNPT coupler, MNPT coupler, FNPT plug, and two MNPT plugs.