National Scientific Headspace Crimp-Top Vials National Scientific Aluminum Seals Pressure-Release. Combining top-notch and uncompromising quality with an affordable price the Thermo Scientific Headspace Crimp-Top Vials Thermo Scientific Aluminum Seals Pressure-Release C4020-6A/ 66064-358 can fulfill your laboratory needs while still offering a great value for the money. Vials feature a beveled crimp finish which gives a much tighter seal than flat crimp surfaces. Manufactured from clear 33 expansion borosilicate glass. Flat-bottom vials feature a slightly longer neck providing a custom fit for Carlo Erba and Agilent autosamplers. Round-bottom vials are designed to fit PerkinElmer Tekmar and Varian headspace autosamplers. Seals have attached septa unless otherwise specified. National Scientific Headspace Crimp-Top Vials National Scientific C4020-6A Aluminum Seals Pressure-Release