These Viton O-rings contain a rubber elastomer O-ring and are for the door seal on the Fast Access Entry Door CF 4.5 inch blind View Port (P106070) and for the door seal on the Fast Access Entry Door CF 6.0 inch with the Window View Port (P106066). The O-ring door seal would limit the high vacuum to 10^-8 Torr range and can be heated to 150 °C for bake-out defined by the Viton O-ring. VitonŽ is well known for its excellent resistance to heat (400°F/200°C) and to aggressive fuels and chemicals. VitonŽ is a registered trademark of DuPont Performance Elastomers.