These PYREX® VISTA™ 2L volumetric flasks provide precise volume measurement. These flasks have sealed necks tooled for No. 27 Standard Taper glass stoppers. The graduation line is sharp and permanent and large blue block letters make the inscription easy to read. These Class A volumetric 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.