This screw-type drain plug is constructed of black polypropylene and features an chemically inert "O" ring for positive sealing. Strong threads maintain sealing under high vibration conditions. Special design prevents cross thread. This drain plug mounts in a 1 Inch diameter hole with 2 (two) number 8 countersunk stainless steel screws. The back side of mounting flange has a groove to hold sealant for positive water proof mounting. Mounting flange is approximately 1 1/2 Inch x 2 Inch. This drain plug is ideal for boat transoms, fish wells, bait tanks, water tanks, coolers, ice chests or almost any application where a positive sealing drain plug is required. This drain plug is not only quick and simple to install, but it also provides a definite cost advantage over outdated, leaking flared-type drain tubes. This retained plug will not get lost.• Type: Threaded Screw-In• Diameter: 1 Inch• Material: Nylon Strong Threads Maintain Sealing Under High Vibration Conditions Special Design Prevents Cross Thread | Supplies Boat Drain Plug in Black