These heavy wall flasks have a protective PVC coating for longer product life and safety. Protective coating helps prevent glass from shattering and reduces spills. Autoclavable (121°C) and resistant to thermal shock. For convenience, the flasks are graduated to show approximate capacity. Tubulation O.D. is 10mm on sizes up through 1000mL. Tubulation O.D. is 12.5mm on 2000 and 4000mL sizes. The tubulation is not coated to allow easy connection of standard size tubing.