SIBATA Class A, Low-Actinic Amber, To Contain, Volumetric Flasks meet ASTM E-288 Class A Specifications & USP Standards for Volumetric Glassware. These Flasks feature machine-blown bodies and heavy-beaded, heavy-tubing necks which are tooled for standard taper stoppers. The graduation line is sharp and permanent; large, white block-letters allow the labeling to be easily read. Each flask also has a large marking square. The low-actinic amber lass provides protection for materials sensitive to light. All sizes are supplied with a glass standard taper stopper.