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. 1.8-425 Thread Small Opening Vials ND8