Poolmaster 12966 Replacement Filter Cartridge for Star Clear Plus C-900 CX900RE Filter The corresponding Pleatco number is PA90-4 and the corresponding Unicel number is C-8409 The top of the replacement filter cartridge is open 4 molded gasket and the bottom is open 4 molded gasket 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