Description General description Angled position makes manipulation of stopcock easier than conventional style. Leak-proof with complete drainage, pressure-equalizing arm, precise needle-valve adjustment, and double-scale graduations. Threaded stopcock (0 to 3 mm orifice for funnels up to 250 mL and 0 to 5 mm orifice for funnels 500 mL and larger) with PTFE plug permits smooth needle-valve adjustment down to 0.1 mL/min flow rate. Double PTFE-ring seals prevent exposure of backup O-ring to corrosive liquids.