Female coupler made of made of zinc-plated steel to prevent rust from moisture-rich environment. Deep knurled socket sleeves on the couplers. Couplers feature a 4-ball positive-locking” mechanism. 100% air-tight seal. Accidental disconnect protection. Designed for general air service and pneumatic tool applications. 1/4 inch body and 1/4 inch NPT thread. 150 PSI maximum working pressure. Air flow 35 SCFM at 100 PSI inlet with 10 PSI pressure drop.