• Weight: 4 oz. 

• Width: 7.25" 

• Length: 21.5625" 

• Area: 100 sq. ft. 

• Top Style: 3" Open 

• Bottom Style: 3" Open 

The Filbur FC-1638 is a replacement spa or pool filter cartridge for the Sonfarrel 100 with Step. The FC-1638 spa filters are made of high-quality polyester and feature an open core measuring 3 inches in diameter. Spa and swimming pool filters work in conjunction with balanced water chemistry to removed bacteria, body oils, lotions, and soaps that can cloud water and cause an unsafe swimming environment. The FC-1638 spa filter cartridges are able to replace the following manufacturer part numbers: Sonfarrel/Martec 2301600, Unicel C-7419, Pleatco PTM100, and Aladdin 19909.