DWK Life Sciences MicroLiter 16mm Screwthread Headspace Vials. MicroLiter 16mm screwthread headspace vials are made from Type 1 borosilicate glass and work well on PerkinElmer™ Aijiren™, CTC Analytics, Shimadzu™, Tekmar™, and other headspace autosamplers. They meet strict tolerances set by the manufacturer of the instrument.