Under sink water filter RC 4 EZ-Change Premium Water Filter, for Culligan RC-EZ-4, IC-EZ-4, US-EZ-4, RC-EZ-3, DuPont WFQTC30001, WFQTC70001, 2K Gallons. with Leading Models: Culligan RC-EZ-1, RC-EZ-3, RC-EZ-4, with IC-EZ, US-EZ, RV-EZ system; DuPont WFQTC30001, WFQTC70001, WFQTC90001.