Lock On Air Chuck 1/4 NPT Closed Flow Brass Tire Air Chuck Set of 2 Features: Lock On Tire Air Chucks - Set of 2 Lock On Air Chucks make tire inflating simple with Rapid Co2 Tire inflation systems.  AIR TIGHT SEAL CHUCK: The locking air chuck is designed with 3 clamps that quickly lock on to the tire valve stem with a simple push. Pull back to release. EASY TO USE: A locking device on the chuck secures to the tire valve stem so the tire can be inflated hands free. The user can operate the tire inflator gauge without worrying about the chuck and tire connection. BUILT TO LAST: The air chuck are made of a solid brass nut and nickel-plated steel. Durable and resistant to oxidation. APPLICATION: Locking Air chuck with a 1 /4 F.NPT are suitable for most tire gauges, inflators and hoses.  CLOSED FLOW AIR CHUCK: The lock on air chuck enables the shutoff valve to shut down the air flow when the stem is not opened. The air only flows when you slide down the sleeve of chuck over the valve stem.