Pentair 274494 Adapter O-Ring Replacement Pool/Spa Filter, Heater and Valve Adapter o-ring replacement Fits Pentair FNS, Nautilus, Nautilus Plus D.E. and TR100C, TR140C, Triton II, Triton C, Triton C-3 pool and spa sand filters Also fits Pentair Minimax NT STD, NT LN and NT TSI pool/spa heaters Also compatible with Pentair HiFlow, FullFlow and Push Pull pool/spa valves Measures 2-3/4-inch length by 2-3/4-inch height by 1/4-inch width