These PYREX® Brand 5660 Class A volumetric flasks feature a fine line capacity mark etched through a narrow red band into clear glass, making a filler unnecessary and providing high legibility, accuracy, and permanence.
The strength of these flasks has been increased appreciably through machine-blown bodies that feature sealed heavy-tubing necks.
Flasks are calibrated "To Contain" and meet 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.