These PYREX® Brand 5640 Class A volumetric flasks feature machine-blown bodies for durability. Heavy-tubing neck accepts glass stoppers. Each flask has sharp, permanent graduation markings. Large white block letters make inscriptions easy to read. The 1-mL and 2-mL flasks are test-tube shaped. Sizes 3000 mL to 6000 mL have pennyhead stoppers.

When taper sizes are given, the first number is the stopper diameter (mm) across the top; the second number is the stopper length (mm). If only one number is given, it indicates the stopper diameter (mm) across the top.