Camco 40324 RV Bumper Cap, 4-Inch Square Vented, Black

If you own a travel trailer or fifth wheel, that hollow square tube across the back of your rig isn't just a bumper. It's where your sewer hose lives. Camco's 40324 bumper cap is the black polyethylene end cap that seals off a standard 4-inch square RV bumper so everything you stash inside stays put and stays clean.

Here's the thing about a rear bumper that doubles as sewer-hose storage. It's open on the end, it sits low, and it spends every mile eating road spray, gravel, and whatever's kicking off the tires ahead of you. Without a cap, your dirty hose slides around, catches wind, and can work its way loose on the highway. Worse, an open bumper is an open invitation. Wasps, mud daubers, and spiders love a dark, dry tube, and once they move in you've got a nest an inch from the hose you handle at every dump station. This cap closes that gap.

What makes it work is the vent holes. They're small, on purpose. Big enough to let air move through the bumper so condensation and hose odor can breathe out, small enough that insects can't crawl in. So you get airflow without the bug problem. That matters more than it sounds, because a sealed-tight bumper traps moisture and a wide-open one collects nests. The vented cap splits the difference the right way.

The fit is designed for the standard 4-inch square bumper you'll find on most trailers and fifth wheels. Ridged sides grip the inside walls of the bumper tube so the cap holds firm at highway speed instead of rattling loose the first time you hit a frost heave. When you do need it off, a squeeze grip lets you pop it out by hand. No tools, no prying, no cracked plastic. Squeeze, pull, done. Pull your hose, then press the cap back in until it seats.

It's molded from durable polyethylene in black, so it shrugs off UV, road salt, and the occasional scrape without going brittle or fading to chalky gray after a season in the sun. Polyethylene won't crack in cold weather the way cheap brittle plastic does when you're winterizing in November, and it holds its shape year after year.

This is a common thing to lose. Caps walk off at campgrounds, get left behind at dump stations, or finally give up after a few thousand miles of vibration. If you've got one open end on your bumper and a hose that keeps trying to escape, this is the replacement. It's sold as a single cap, so grab one for each open end if your bumper's capped on both sides.

Installation is about as simple as RV maintenance gets. Clear any debris from the mouth of the bumper, line the cap up with the square opening, and press it in until the ridged sides bite and it sits flush. That's the whole job. First-time trailer owner or full-timer who's done this a hundred times, either way you're looking at thirty seconds at the campsite.

One last note on where it's made. This cap is manufactured in the USA, which is a small thing until you've bought the bargain-bin version that arrived warped and wouldn't seat. A cap that actually fits the bumper and holds its shape is worth the couple of extra bucks, especially for a part whose whole job is staying put while you drive. The packaging is labeled in both English and French, so it's the same part you'll find on shelves across North America. Keep a spare in the storage bay and you'll never get stuck at a dump station wrestling a loose hose back into an open bumper again.