VEE GEE Scientific Separatory Funnels with Stopper meet ASTM E-1096 Type 4 Specifications for Classification, Design, and Markings. These separatory funnels feature smooth tooled tips, large, white block letters, and large marking squares. Supplied with PTFE stopcocks to eliminate freezing and lubricant contamination and to provide a precision fit within the barrel. The stopcock bores, body openings, and stem are carefully aligned for even liquid flow with fast cut-off. Made from Schott DURAN® borosilicate tubing with a low coefficient of expansion. Borosilicate tubing also provides uniform wall thickness resulting in the optimum balance between thermal shock resistance and mechanical strength. All supplied with a polyethylene ST stopper.