For professional installers, includes clear filter housing for monitoring cartridge life, and pressure release valve. Installed on standard plumbing pipe to effectively reduce rust, sediment, chlorine, and odors where water lines enter homes for clean and better tasting water flowing to all faucets and appliances. Nos.TO1, RS1, RS2 or RS3 filter cartridges,and No.K4 replacement o-ring sold separately. 13-1/4"L x 4-1/2"W.