Reduce sediment, rust, scale, dirt and more from up to 12,000 gal. of drinking water. The Culligan CW-F-D whole house water filter replacement cartridge is built to fit heavy duty Culligan whole house filtration systems that use 9-3/4 in. x 2-1/2 in. cartridges or any brand system that uses standard 9-3/4 in. x 2-1/2 in. filter cartridges. Replace every 3 months for cleanest tasting results. This model ships as a 2-pack.