We also supply encapsulated o-rings where one material is covered with continuos layer of another material, it have a core of elastomer that is completely covered with a seamless sheath of FEP fluoropolymer. the elastomeric core isnormally is FKM or silicone, the unique combination forms a highly effective, long lasting seal for the most demanding applications. These O-rings can withstand a temperature range of -60°c to +250°c depending upon the choice of elastomer core.