Completely clear your water lines with RV blow-out plugs. Screw the plug into the city water inlet, open all drains and faucets, attach and activate air pump until all lines are clear! Aids in water removal Eliminates dilution of antifreeze application in recreational vehicles, mobile homes and boats Patented Directions: Screw into city water intake fitting Apply air pressure using an oil-less air compressor DO NOT EXCEED 50 psi air pressure