These Pyrex® distilling flasks are used are suitable for microchemical applications. The sidearm on all sizes (except 125mL) is approximately 77mm below the top of the neck at an angle of 75°. Adaptable for use with thermometers calibrated for 76mm immersion. The sidearm of the heavy duty 125mL flask is located approximately 137mm from the bottom of the flask to meet the requirements of ASTM E-1405 and can be used in ASTM tests D-86, D-233 and D-447. Flasks take a rubber stopper.