These Class A volumetric flasks feature a protective PVC coating for longer product life and safety. Protective coating helps prevent glass from shattering and reduces spills. Flasks are autoclavable (121°C) and resistant to thermal shock. The strength of these flasks is increased by sealing machine-blown bodies to heavy-tubing necks tooled for ST glass stoppers. For replacement stoppers see Cat.No. 1-7650. The graduation line is sharp and permanent and large white block letters make the inscription easy to read. These flasks have been manufactured to Class A tolerances as established by ASTM E- 694 for volumetric ware, ASTM E-542 for calibration of volumetric ware and ASTM E-288 for volumetric flasks.