2.0 mL, 8 mm Caps and Septa Material: (preassembled) Fit all 2.0 mL, 12 x 32 mm, screw-thread 8 mm/425 vial-based autosamplers. Choose preslit caps (available for some vials) to reduce the risk of needle bending, release vacuum from high-volume injections, and improve injection reproducibility when greater than 20% of vial volume is withdrawn.