Sta-Rite Cristal-Flo High rate Sand Filters Clamp Knob WC3622 Model PTM135, Posi-Flo II Cartridge Filters PTM Series - Models S-200BP-1M, S240BP-1M, S240BP-2S, T-300BP-2, Max-E-Glas/Dura-Glas Series - "Full Rate & Up Rate", Max-E-Glas II/Dura-Glas II Series