Thermo Scientific™ Septa for 8-425 Screw Thread Caps are constructed of PTFE, PTFE/rubber, or PTFE/silicone to suit a variety of HPLC, GC and IC applications. Choose from Thermo Scientific™, Thermo Scientific™ National™, and Thermo Scientific™ Chromacol™ brands. Product Overview. Documents. Description. Septum for 8-425 Screw Caps