Quick Products Blow Out Plug w/ Brass Quick Connect. Any water left in the lines over the winter months may freeze or dilute your antifreeze which can lead to leaking and burst pipes. The Blow Out Plug attaches to your RVs city water inlet to allow the attachment of an oil-free air compressor to blow out any remaining water. Simply open the faucets attach the air compressor and watch all the water leave your water lines. (Note: Do not exceed 50 psi from the air compressor when clearing the lines.) Connection size: 3/4"-11 NH. Features of Quick Products Blow Out Plug With Brass Quick Connect Makes clearing water lines simple protecting your RV from potential bursting pipes in the winter months Attaches to RVs city water inlet 3/4"-11 NH Quick connect end allows easy hook up to an oil-free air compressor Brass construction is built to last Do not exceed 50 psi while clearing lines Package Contents: Quick Products Blow Out Plug With Brass Quick Connect Quick Products QP-BOPQCB: Blow Out Plug w/ Brass Quick Connect