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. 2ml clear snap top hplc vials for sale--Lab Vials Manufacturer. 2ml Amber Screw HPLC Vials, caps, septa, and inserts working as a whole to prevent sample degradation and loss of samples caused by evaporation.