Mar 22, 2020 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 With Our Simplified Selection of Chromatography Vials - Restek. 2.0 mL, 9 mm Short-Cap, Screw-Thread Vials, 12 x 32 mm. Fit all 2.0 mL, 12 x 32 mm, 2.0 mL, 8 mm Autosampler Vial Convenience Kits (Vials, Caps & Septa).