These 30mL Corning Pyrex dropping bottles are recommended for use when preventing contamination by solubility or pH change is important. Stopper is not covered by ground glass joint specifications, but ground to an interchangeable 1:10 taper. Pipet capacity is 0.25mL. Material: Borosilicate Glass Code 7740. Capacity: 30mL. Bottle Style: Dropping. Neck Style: Narrow Mouth. Top Style: Ground. Bottle Shape: Cylindrical. Stopper Style: Hollow. Glass Height with Stopper: 110mm (approx). Height without Stopper: 73mm (approx). Outer Diameter: 35mm (approx). Not sterile. Reference: ASTM D-281. Corning #: 1340-30.