Pleatco PCC130-PAK4 Replacement Cartridge for Pentair Clean and Clear Plus 520, Waterway Crystal Water, Pack of 4 Cartridges Replacement filter for pool and spa cleaning systems 50% open ABS free flow cores maximize water flow through REEMAY filter media Antimicrobial end caps resist chlorine degradation and provide support to filter material for a longer life span 7" Outside Diameter, 3" Inside Diameter and 32" Length Made in the USA