Poolmaster 12354 Replacement Filter Cartridge for Jacuzzi Aero, Caressa, C/top Filter Equivalent to the following replacement filter cartridges; Pleatco PJW23 and Unicel C-5601 The top of the replacement filter cartridge is closed with string loop and the bottom is open 2-1/8 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