Griffin Low Form Beakers are made of 3.3 borosilicate glass. Double-Metric Scale, Heavy-Duty, beaded rim and a spout designed to have excellent pouring characteristics., white marking spot, and uniform wall thickness throughout. 3.3 borosilicate is the highest level of inert glass available. Designed from ASTM Specification E960, Type I requirements. Karter Scientific is a registered trademark in United States of America. To maintain quality control, authorized permission is required in the resale of our products.