Equivalent to the following replacement filter cartridges; Pleatco PWK30 and Unicel C-6430 * The top of the replacement filter cartridge is open 1-15/16 and the bottom is open 1-15/16 * 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