The CMP 817-3501 R is a compatible replacement for the following spa filters:
The Custom Molded Products 817-3501 Comp. Pool Filter is a spa filter replacement with Open top/bottom styles measuring 2 1/8". This compatible Custom Molded filter effectively purifies your swimming pool or spa's water through the use of 35 sq. ft. of quality media. This pool filter cartridge is constructed with dimensions of 4 15/16" in diameter and 9 1/4" in length.