Vial kit, crimp top, headspace, clear, 20 mL, silver aluminum caps with safety feature, certified, flat bottom, molded PTFE/black butyl septa, 100/pk. Vial size: 22.75 x 75 mm (20 mm cap) Product details. Headspace Vials, Caps and Kits | Aijiren Tech Scientific - JP. 18mm Screw top headspace vials, caps, septa.