High Temperature Silicone Rubber O ring (1 pair) for 25-26 mm dia Alumina or Quartz Tube - EQ-SOR-25
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