SIBATA Class A, To Contain, Volumetric Flasks with Snap Cap 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 snap-cap fit. The graduation line is sharp and permanent; large, white block-letters allow the labeling to be easily read. Each flask has a large marking square. All sizes are supplied with a snap cap.