The dropping funnels manage the slow content transfer with the featured stopcock. Stoppers disconnect the funnel and pressure equalizing arm leaving sensitive fluids isolated and unexposed. Typically cylindrical, the laboratory glassware comes with or without calibrated graduations for visible measuring during reagent addition. Protected drip stems will not extend beyond standard taper joint and the ground outer joints allow vessel to fit securely into reaction flask. Dropping funnels are available in different capacities.