Corning Pyrex 300mL Hydrometer Cylinders have a large hexagonal base sealed to the cylinder body to increase stability. Breakage is minimized by the heavy wall construction. Meets ASTM specifications D-287 and E-100. Material: Borosilicate Glass Code 7740. Capacity: 300mL. Cylinder Style: Hydrometer. Top Style: Beaded Rim. Stopper Style: No Stopper. Reuseable. Bumper Guard: No. Height: approximately 381mm. Outer Diameter: approximately 39mm. Corning #: 2962-300.