Cartridge element for Rainbow CL29 filter has a pleat count of 41. Top cap opening is 1-1/16" Other Products Using This Part: R172502B Dynamic Series II Filter RTLB25, Bottom load filter w/3oz High Flow Cartridge Filter R172502J Dynamic Series II Filter RTL25, Top load filter w/3oz High Flow Cartridge Filter R172532 Dynamic Series III RCF25, Top load, High Flow Cartridge Filter R172522 Dynamic Series II RCF25, Top load, High Flow Cartridge Filter R172523 Dynamic Series III RCF25, Top load, High Flow Cartridge Filter R172502 Dynamic Series II Filter RTL25, Top load filter w/3oz High Flow Cartridge Filter