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