Headspace Crimp/Screw Top Vials, 20 mm, PerkinElmer | VWR. Headspace Crimp/Screw Top Vials, 20 mm, PerkinElmer. Vials Chromatography Vials. These headspace vials are manufactured from Type I borosilicate glass, which meets all USP, JP, and EP Pharmacopeia requirements. Clear galss. Resistant to high temperature.