Microvolumetric Class A flasks are individually serialized and supplied with a Certificate of Identification and Capacity. Flasks are designed for microchemical work in accordance with the recommendations of the Committee of Microchemical Apparatus, Analytical Division of the A.C.S. To improve the stability of this small flask, a hexagonal base, similar to those on all cylinders, has been added. The graduation line is sharp and permanent and the white markings are easy to read. Flasks with capacities of 1, 2 and 5 mL come with a No. 8 PYREX stopper while 10 and 25 mL capacity versions are supplied with a No. 9 stopper. Reference: ASTM E-237.