Camco Brass Blow-out PlugCompletely clear your water lines with the Camco Brass Blow-out Plug. Use this plug for winterizing to prevent your water lines from freezing. Using a blow-out pump to clear your water lines will help extend the life of your water heater. For use with 1" diameter drains. Instructions: Screw the blow-out plug into the city water inlet; Open all drains and faucets; Attach and activate air pump until all lines are clear;