Thermo Scientific™ 8mm Autosampler Vial Crimp Caps. 8mm Crimp Top Closures provide a leak-resistant seal, feature 4mm openings and are available with a variety of septa materials with and without liners. Pricing and Availability. Fisherbrand™ 8mm PP Screw Seal, Black, Center hole, 8-425 thread, Assembled septum.