SIBATA 2307A-Series Low-Actinic Amber Volumetric, To Contain Flasks meet ASTM E-288 Class A Specifications & USP Standards for Volumetric Glassware. Feature machine-blown bodies and heavy-beaded, heavy-tubing necks, tooled for ST stoppers. The graduation line is sharp and permanent; large, white, block-letters allow the labeling to be easily read. Features a large marking square. The low-actinic amber stained glass provides protection for materials sensitive to light. All sizes are supplied with a glass ST stopper.