OMNIFilter K4-M6-S06 Accessory O-ring Replacement O-ring kit for OMNI Filter undersink systems Make cartridge changes easier by replacing the O-ring at least once a year For use on OMNI Filter CBF1, CBF3, SFM2, USM2, OCT2, OT32, RO2000, RO2050 and U30 housings Also fits DuPont and Culligan undersink filter systems Includes 4 commonly used O-rings