The 18mm Screw Headspace Vial and Cap with electromagnetic screw seals used for CTC is novel in the headspace vial market dominated by crimping necks. Especially for magnetic caps that are difficult to crimp, screw caps are a convenient choice. 18mm Screw Headspace Vial and Cap with aluminum skirt and magnetic center plate, it is easy to crimp and remove the cap. 18mm Headspace Vial and Cap is preferred for the following instruments: CTC PAL, Varian, Gerstel, Atas, Shimadzu, Aijiren.