Poolmaster 13045 Replacement Filter Cartridge for XStream XXC1000 CCX1000RE Filter The corresponding Pleatco number is PXST100 and the corresponding Unicel number is C-8311 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