Camco 40310 Magnetic Sewer Hose Bumper Cap, 4-Inch Square

If you store your RV sewer hose inside a square metal bumper on the back of your rig, the end cap is the piece that holds the whole setup together. The Camco 40310 is that cap. It's a single black polyethylene cap built to fit a metal 4-inch square sewer hose bumper, and it quietly does three jobs at once. It seals the open end of the tube. It gives your hose a place to attach. And it lets the bumper breathe so the inside dries out between trips instead of sitting damp.

The cap is magnetic, and that's a bigger deal than it sounds. Picture yourself at the back of the coach with dirty gloves on, ready to roll to the next site. A magnetic cap snaps onto the metal bumper end and stays put, so you're not wrestling a threaded cap or fighting a stiff friction fit every single time. Pop it off, slide your hose out, snap it back on. That's the whole routine, and it takes about two seconds.

Then there are the bayonet lugs. Most RV sewer hoses use a bayonet fitting, the same quarter-turn lock you already deal with at the dump station. The 40310 carries those lugs right on the cap, so you can twist your hose onto the cap end and lock it in place. That keeps the hose captured and organized inside the bumper instead of loose and sliding back and forth every time you hit a bump in the road.

The vent holes matter more than most folks expect. A sealed metal tube with a used sewer hose inside is a recipe for trapped moisture and stale odor. The 40310 has vent holes so air can move through the bumper and the hose can actually dry. And because open vents would be a wide-open door for wasps, spiders, and mud daubers, Camco backed them with an insect screen. Air gets in. Bugs stay out. It's a simple bit of engineering that saves you a nasty surprise the next time you pull the hose.

The body is polyethylene, the same tough plastic Camco runs across its RV sanitation gear. It handles the grime and the occasional knock that comes with living at the very back of your rig, and it won't rust the way a bare metal cap eventually would. The black finish keeps it low-key against most bumpers, so it looks like it belongs there.

Fitment is straightforward. This is the cap for the metal 4-inch square sewer hose bumper. If your RV came with a square steel bumper set up for hose storage, or you added one yourself, the 40310 is the part that finishes the end. It ships as a single cap in a retail package, which makes it an easy direct replacement when your original cap cracks, walks off at a campground, or loses its magnet.

Here's how it plays out on a travel day. You break camp, give the hose a rinse, feed it back into the bumper, and twist it onto the bayonet lugs. The cap snaps on with the magnet and you're done. On the drive over, the vent holes keep the inside from turning into a swamp, and the screen keeps the local bug population out of your storage. It's a small part, but it's the difference between a tidy hose setup and a mess in your bay.

It's not fancy, and it doesn't pretend to be. It's a sewer bumper cap. But it's the right one for a 4-inch square metal bumper, it's a genuine Camco part with the correct bayonet lugs and insect screen, and it handles the three things a bumper cap actually needs to do. Whether you're swapping out a tired cap or setting up hose storage for the first time, the 40310 gets you squared away.