CX900F O-240 U9-228 O-Ring for Hayward Star-Clear Plus Cartridge Filter Series & Separation Tank U9228A Replacement Parts (1/Pack) + Lubricating Grease Fits C751 C900 C1200 C175 Cartridge Filters Fits hayward star-clear plus cartridge filter series and separation tank Approximately 9.88" ID x 10.4" OD x 0.28" Thickness Material: Buna-N (nitrile butadiene rubber) CX900F O-240 U9-228 O-Ring for Hayward Star-Clear Plus Cartridge Filter Series & Separation Tank U9228 Replacement Parts (1/Pack) + Lubricating Grease