The mobile phase bottle caps are made of polypropylene with a PTFE insert. The O-rings are made of Viton® and coated with PTFE. The caps, inserts, and O-rings are made for use with GL 45 screw thread  bottles. The ring has an outer diameter of approximately 36.4 mm and an inner diameter of approximately 28.6 mm.

Mobile Phase Bottle Caps Product Page