The Muskin FD-40 R is a compatible replacement for the following pool and spa filter cartridges:
The Muskin Pools FD-40 Comp. Pool & Spa Filter is a spa filter cartridge measuring 6 1/4" in diameter and 8" in length with 2 3/8" Open top & bottom styles. Featuring 20 sq. ft. of media area, this compatible Muskin Spas filter purifies swimming pool & spa water.