Hybex™ Erlenmeyer Flasks are manufactured from high quality, borosilicate 3.3 glass. A low coefficient of thermal expansion (3.3), provides temperature resistance that is far superior to that of standard lab glass (or soda lime glass) . Hybex glass is designed to withstand high temperatures, making them ideal for shaking applications, media preparation and long-term storage. The standard erlenmeyer flasks have permanent, white enamel graduations for volume measurement and a white identification box for marking or coding.