Class A, USP, certified volumetric flasks. These are supplied with a glass stopper with a dripping tip. Available in both transparent and amber color. High contrast blue enamel print on transparent flasks, and white on amber flasks, represent the optimum combination of resistance and readability. Available in all ISO sizes from 5mL to 1000mL. Made of low expansion coefficient, chemically resistant borosilicate 3.3. Volumetric flasks are indispensable for preparing dilutions and standard solutions. All BLAUBRAND USP volumetric flasks are supplied with a batch number and an accompanying USP batch certificate in the original packaging.