Karter Scientific Volumetric Flasks are manufactured from polypropylene(PP) material. Screw caps are polypropylene as well. Compliance with ISO 1042 Class B tolerances for consistent quality and dependability. Break resistant and excellent chemical resistance. No meniscus to confuse readings. Calibrated "To Contain" and "To Deliver" at 20°C. Flat bottom. Printed permanent color graduation line and oval marking spot for ease in reading fluid levels. Autoclavable and leakproof.