Unique design of this addition funnel permits solutions to be prepared using a magnetic Stir Bar. Side arm has a 2mm high vacuum glass T-Bore stopcock having a S.S. constant pressure retension device for evacuation and purging of both the funnel and lower vessel. Lower valve is a 0-4mm Chem-Vac™ Chem-Cap® valve. The top outer and lower inner standard taper joints are the same size. The 50mL and 125mL sizes are graduated in 1.0mL subdivisions, while the 250mL has 5.0mL subdivisions.