Headspace crimp vials, the value have 6ml,10ml, 20ml clear and amber to choose, the bottom have flat,rounded and rounded-flat,etc. Match with crimp cap for GC analysis. 20mm Crimp GC Vials. 10ml Crimp Top Headspace Vial has a very good seal and can be used for volatile samples, but it needs to be used with 20mm Hand Crimper to seal the vials