Poolmaster 12659 Replacement Filter Cartridge for Star Clear C-500 CX500RE Filter Equivalent to the following replacement filter cartridges; Pleatco PA50 and Unicel C-7450 The top of the replacement filter cartridge is open 3 and the bottom is open 3 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