1. Screw 8-425 (8mm, N8) HPLC Vial, Cap, Septa and Inserts . They are made with a 5.5 mm opening. These vials are designed to work on most autosamplers that use 12mm x 32 mm crimp style vials. They offer the convenience of screw thread vials for instruments that were originally designed for crimp top vials.