PYREX 100mm diameter watch glasses are designed to fit 600mL PYREX beakers. They possess high chemical durability, thus preventing contamination of solutions. They are molded to the same radius of curvature for convenient stacking. The heavy wall and uniform fire-polished edge provide mechanical strength. The outside diameter cannot be controlled within close limits and a slight degree of out-of-round can be expected to occur. Material: Borosilicate Glass Code 7740. Top Style: Heavy Duty Rim. Fits Griffin Beaker Size: 600mL. Diameter: 100mm (Approx). Reusable. Corning #: 9985-100.