Camco's Mag-Cap Magnetic Bumper Cap fits on the end of most metal 4" square RV bumpers. High-strength Neodymium magnets keep the bumper cap in place. The cap has small holes for airflow and doubles as an insect screen. The built-in lug adapter is compatible with any bayonet-style sewer hose fitting. The end of the sewer hose locks onto this cap, preventing the hose from sliding around in the bumper. When you remove the cap, it pulls out the sewer hose.