Easy Flushing and winterization of marine engines, a/c, and generators All caps are sold individually, please measure your strainer cap prior to ordering Works on all Perko model 493 Sea Strainers with 3.5" diameter cap (round edge to round edge) Come equiped with a garden hose connector for ease and convenience of use Constructed of pressure molded durable polyurethane and equipped with a chemical resistant silicone gasket Available in three sizes to fit any Perko Model 493 series Sea Strainer. Makes flushing and winterizing your raw water cooled boats easier than ever! These Flush Caps make descaling with Barnacle Buster, fresh water flushing, and winterizing your raw water cooled equipment a breeze! No Need to constantly remove your hoses to gain access to your strainer, as you can simply swap the stock cap for ours and use a standard garden hose to flush or winterize your engines, generator, or air conditioners. Temporarily replacing your strainer cap allows you to effortlessly flush your strainer and adjoining system with minimal effort. These Flush Caps are constructed of a durable, impact resistant, pressure-molded rigid plastic. The 1/2", 3/4", 1", and 1.25" are pressure-molded rigid plastic with a 3/4" NPT thread fitted with a swivel head female garden hose fitting. The 1/2" and 3/4" sized caps are typically used for most marine air conditioning water intakes and generators up to approximately 8KW in size. The 1.25" size is standard on most gas motors up to 8.2 liters in displacement. The gaskets are custom made silicone, and are more chemically resistant than the stock rubber gaskets. The 1.50"-2.50" caps are made with a 316 stainless steel 1.25" Hose barb fitting with the housing threaded in 1" NPT. This is to accommodate the greater water flow requirements of larger diesel powered vessels. These caps can utilize 1.25" ID hose such a standard bilge pump hose which can be economically sourced at your local marine supply or hardware store (Lowe's and Home Depot). Cap sizes are by either strainer model # size, or the internal diameter of the hose connected to your strainer. If you are unsure contact us and we will help determine the correct caps for your boat. Cap colors vary, however whenever possible we will send matching sets when multiple caps are ordered at the same time.