Description. Thermo C5000-54B 9mm Autosampler Vial Screw Thread Caps Blue 9mm with Red PTFE/White Silicone Septum,100/pk. Prevent septa push through and over- and under-tightening. With Advanced Vial Closure System (AVCS) technology built into 9mm Thermo Scientific™ 9mm Autosampler Vial Screw Caps and Septa you will get an optimal, consistent