Pentair 27001-0130S Spring Check Valve Replacement Sta-Rite Pool/Spa D.E. and Cartridge Filter Spring check valve replacement Fits Pentair Sta-Rite PLM and System 2 modular media pool and spa cartridge filter models PLM100, PLM125, PLM150, PLM175, PLM200, PLM300 Also fits Pentair Sta-Rite PLD and System 2 modular pool and spa D.E. filter models PLD50-DE, PLD70-DE Measures 1-inch length by 1-inch height by 1-inch width