Pyrex® Lifetime Red™ volumetric flasks have the capacity mark etched as a fine line through a narrow red band into clear glass, making a filler unnecessary and giving high legibility, accuracy and permanence. The strength of these flasks has been increased appreciably through machine-blown bodies to which are sealed heavy-tubing necks. These 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. Calibrated "to contain." Available with snap caps or glass ST stopper.