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. For storage of media and cultures, the capped flasks include an autoclavable polypropylene cap & drip-ring. Optional cap colors are available, as well as PBT material caps for temperature applications up to 180°C. (Threads are standard GL-45 for compatibility with a wide range of cap types from various manufacturers, including phenoic caps, vented caps, etc.)