Thermo Scientific™ 8mm Autosampler Vial Septa. Septa for 8-425 Screw Thread Caps are constructed of PTFE, PTFE/rubber, or PTFE/silicone to suit a variety of applications. Pricing and Availability. Thermo Scientific™ SUN-SRi™ 20mm Septa. Sun-SRI provides high quality vials, caps, seals, septa, and closures to meet or exceed original