R&S 3-58 O-Ring for: Aquasana Model AQ-CWM-D-B and AQ-PWFS-RB1 This is a Food Grade EPDM material EPDM-Has higher temperature range than Buna-N and is used with Foods and Water Also Has Better Chemical Resistance Durometer 70A Made In USA Complete Return Policy O-Ring problems: Send us your old O-Ring that worked and we will find you the proper O-Ring.