The dropping funnels or addition 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. Pressure equalizing models are equipped with a glass tube that connects to the ground glass joint from the bulb of the funnel. Dropping funnels are available in different capacities.