These Viton O-rings are for the door seal on the Fast Access Entry Door CF 12.0 inch with Window View Port (P1012620). 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.