screw top headspace gas chromatography metal cap aijiren Vial size: 22.75 x 75 mm (18 mm cap) 5188-2759 Caps/septa, screw, headspace, steel, high temperature septa, certified, 18 mm, 100/pk. Cap size: 18 mm Vial, crimp top, headspace, amber, graduation marks and write-on spot, flat bottom, certified