Pentair 192320 O-Ring Bulkhead Replacement Pool and Spa Filter O-Ring bulkhead replacement Fits Pentair FNS and FNS Plus pool/spa D.E. filter models FNSP 24, FNSP 36, FNSP 48, FNSP 60 Also fits Pentair Nautilus and Nautilus Plus pool D.E. filters models NSP36, NSP48, NSP60, NSP72 Also compatible with Pentair Clean & Clear Plus cartridge filter models CCP240, CCP3201, CCP4201, CCP5201 FNS plus made of 2-137 buna N 70 shore