Check the listing for details. US Hardware Holding Tank Bayonet Cap 3" Black Plastic. Color: Black, Condition: New, Made in MEXICO. Listed at 27.92 USD. SECURE HOLDING TANK SEALING: US Hardware RV-509B bayonet cap delivers a tight, leak-resistant seal for RV waste-holding tanks, preventing odors and spills during storage or transit. 3-INCH BLACK PLASTIC CONSTRUCTION: Molded from durable black plastic, the cap measures 3 inches in diameter and is designed for single-unit use, arriving carded for easy retail display. IDEAL FOR RV WASTE SYSTEMS: Installs quickly onto standard 3-inch bayonet fittings found on most RV black- and gray-water tanks, making it an essential accessory for campground hookups and dump-station visits. RUGGED ONE-PIECE DESIGN: The solid plastic body resists cracking and UV damage, ensuring long-lasting performance and dependable protection for your RV plumbing system.