Class A volumetric flasks are available with a PTFE or glass stopper. Constructed of glass with uniform wall construction provides superior strength and durability. These volumetric flasks have a wide mouth that allows easy access for pipettes. Easy identification is achieved with large, easy-to-read markings. Flat bottoms are ideal for precise stirring with standard stir bars. The 5- to 250-mL capacity flasks are calibrated to meet ASTM E288 standards.