Set of 1 KF-25 Vacuum Fittings, Aluminium Centering Ring, ISO-KF Flange Size NW-25, with FKM viton O-ring: Amazon.com: Industrial & Scientific
Ochoos 10PCS/lot Rubber Ring Black FKM/Viton O Ring Seal 1mm Thickness OD4/5/6/7/8/9/10mm Rubber O-Ring Seal Gasket Oil Ring Washer - (Color: OD4mm): Amazon.com: Industrial & Scientific