Pleatco PCC105-PAK4 Replacement Cartridge for Pentair Clean and Clear Plus 420, Pack of 4 Cartridges Replacement filter for pool and spa cleaning systems Material weight : 4 ounce / yard square. 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