Grey, high-temp plastic bulk-head fitting for putting a fitting into a plastic cooler (rectangular and round coolers.) Has 1/2" female threads on the interior. It requires that you drill a 1" hole all the way through a cooler and a 2.25" in the outer shell plastic and insulation. This is the same bulkhead fitting we used to use to install thermometers and ball valves in Rubbermaid brand coolers. Replacement part for pre 2014 modified coolers. (Currently manufactured with PVC 1).