4.Vials are manufactured of Clear or Amber borosilicate glass. Features. 1) 8mm screw vials can be used on all common autosampler. 2) Standard narrow neck design for GC and HPLC. 3) 8mm wider opening for easy puncture. 4) 8mm PTFE/silicone septa, has excellent chemical inertness, acid and alkali resistance. 5) 8mm screw black open top pp caps.