VEE GEE 20231 Series Erlenmeyer Flasks meet ASTM E-1404 Type I, Class 1 Specifications for Classification, Design, Capacity & Dimensions, and Markings. Made from high-quality borosilicate tubing for exceptional quality. Feature heavy-duty rims to reduce chipping; white, permanent graduations and a large marking square. Manufactured with uniform wall thickness which offers optimum balance between thermal shock resistance and mechanical strength. Accuracy: ±5% of full capacity. VEE GEE Laboratory Glassware Catalog