The unique offset design of this addition funnel permits solutions to be prepared using a magnetic stirbar and stirrer and still add the material in portions. The sidearm has a 2 mm T-bore high vacuum glass stopcock with a constant pressure retention device. The lower valve is a 0-4 mm Chem-Cap®. The top outer and lower inner standard taper joints are the same size. The 50 mL and 125 mL sizes are graduated in 1.0 mL subdivisions, while the 250 mL has 5.0mL subdivisions.