This is a DEVPH4090 1/4" Female THD Bayo Coupler. This is a air fitting 1/4" NPT quick disconnect coupler female. Quick universal coupler can be used with most US european couplers. Safety lock reduces the risk of possible injury or damage due to accidental air line disconnect. Once the coupler is engaged, turn the regulator ring to lock & regulate the air flow. Built-in air flow regulator opens up 85 cfm of air. Pressure release, no whiplash when disconnecting tools.