Thermo Scientific™ 13mm Autosampler Vial Septa. 13mm Septa for use with threaded caps Snap/Crimp Caps are available in PTFE/ Red Rubber, PTFE/Silicone or Red PTFE/White Silicone/Red PTFE. Pricing and Availability. Fisherbrand™ 43.2mm Septum for SCHOTT Screw Caps. Most septa are laminated on one side with PTFE for high chemical resistance