20PC/lot Rubber Ring NBR Sealing O-Ring 5mm OD22/25/28/30/32/34/35/36/38/40/42/45/48/50mm Nitrile O Ring Seal Oring Gasket Ring - AliExpress
Centering Ring KF 25 With Viton® O-Ring, KF 25 (NW 25), Stainless Steel, The centering ring contains a rubber elastomeric o-ring. Those are also recognized as NW10, NW16, NW25, NW40, or KF-10