PYREX® borosilicate glass.

Flasks feature sharp, permanent graduation line and large white block letter inscriptions. Body is machine-blown with sealed heavy-tubing neck for increased strength. Hollow glass ground NS stoppers, where included, are interchangeable.

All flasks are graduated to Class A volumetric tolerances and calibrated to meet ASTM specifications E-694, E-542, and E-288. Certified flasks are individually serialized and supplied with NIST-traceable certificate of identification and capacity.