Poolmaster 12912 Replacement Filter Cartridge for CFR-75 42-3509-00-R Filter Equivalent to the following replacement filter cartridges; Pleatco PJ75-4 and Unicel C-9475 The top of the replacement filter cartridge is open 5-13/16 and the bottom is open 6-1/16 Break-resistant bands keep pleats separated for greater flow, filtration and add longer life to cartridge High quality spun bonded polyester material for exceptional water filtration Premium grade polyurethane and plastisol end caps