Pentair 273513 O-Ring Bleeder Replacement Pool/Spa D.E. and Sand Filter O-ring bleeder replacement Fits Pentair Nautilus and Nautilus Plus pool/spa D.E. filter models NS24, NS36, NS48, NS60, NS72, NSP-24, NSP-36, NSP-48, NSP-60, NSP-72 Also fits Pentair FNS pool and spa D.E. filter models FNS 24, FNS 36, FNS 48, FNS 60 Also compatible with Pentair Triton C, C-3, TR100C and TR140C pool/spa sand filters Measures 1/2-inch length by 1/2-inch height by 1/4-inch width