Headspace Vials, Caps and Kits | Thermo Fisher Scientific - UK 20mm Clear Headspace Crimp Vial, Beveled Edge, Round Base (C4020-2) Silver Pressure Release Crimp Cap, 7.5mm hole (C4020-32AP) Tan PTFE/White Silicone. 000. 20-HSVST20-CP. 8mm Clear Headspace 20mL Screw Vial, Round Bottom, (20-HSV) Silver Steel Screw Cap, 8mm hole (8-MSCST20) 8mm Blue Silicone/ Natural PTFE.