Pentair 24850-0009 25-Inch Cord O-Ring for Tank Replacement for Select Sta-Rite Pool and Spa Filters Cord O-ring for tank replacement Fits Sta-Rite System 3 Modular Media SM series pool and spa cartridge filter model S8M150, S8M500 Compatible with Sta-Rite System 3 SD series pool and spa D.E. filter model S8D110 Fits with Sta-Rite System 3 SS series pool and spa sand filter model S8S70 Measures 25-inch size