Pleatco PRB25-IN-4 Dynamic Series II and III - RTL/RCF, Series I - Model RDC, Series IV - DFM, DFML, Waterway, 1 Cartridge 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 13-5/16-by-2-1/8-by-2-1/8-inches Made in the USA