Sample vials with screw cap, clear Scherf Prazision Test tubes, threaded, 50 ml, 90 x 30 mm, DIN 25, C40903000F0C2. 20 mm Headspace Vials, Septum, and Caps. Thermo Scientific headspace vials are available in clear or amber glass with a round or flat base, a crimp seal with a beveled or square edge finish, or with a screw-thread finish.