The washer is a replacement for the washer attached to filter pump connection hoses. It is included with Bestway and Flowclear cartridge and sand filter pumps. It is also a replacement for washer that is included in Fast Set, Steel Pro, Steel Pro MAX, Power Steel, Hydrium and Coleman pool sets that include a cartridge or sand filter pump. The replacement washer will connect the filtration system’s hose to reduce the amount of water that leaks out.