These caps are for use with storage tubes

With 2 mm bore stopcock for evacuating or introduction of inert gases. The standard taper 14/35 or standard taper 24/40 joints are used when it is necessary to evacuate completely. The standard taper 14/20 joint is used when there is more concern about grease entering the system. Tube outlet is 8 mm O.D. Fabricated from borosilicate glass.