250mL 2-Neck Flask, Reaction, 24/40 Joint Size, Valve, Airfree, Schlenk. Round bottom 2-neck flask having standard taper outer joints, both being of the same size. Available with a choice of a 2mm high vacuum glass stopcock having a Stainless Steel constant pressure retaining device or a 0-4mm Chem-Cap Airfree inlet valve. Side neck can be fitted with a CG-3022 septum stopper for sampling or cannula transfer.