Description General description Viton® A linear copolymer of vinylidene fluoride and hexafluoropropylene; good chemical resistance Silicone Elastomer with high-temperature and ozone resistance FETFE® Fluoroelastomer with TFE additives and high chemical resistance CAPFE A resilient rubber core encapsulated in nonporous FEP O-ring measurement 1. Measure the I.D. and wall thickness (mm) of the existing O-ring. 2. Locate a replacement in the tables that follow. 3. Ace Glass part numbers are provided for convenience. Legal Information FETFE is a registered trademark of Ace Glass, Inc. Viton is a registered trademark of E. I. du Pont de Nemours and Company