1. Does not come with caps. ND8mm Screw Thread Autosampler Vials are made of clear Type 1, Class A Borosilicate Glass with a writable label for sample identification. 2. Sample Vials with unique thread design ensures consistent seal and can be reused, not volatile, easy to use 3. Screw Neck Vials ND8, small opening, 8-425 thread 4.