A volumetric flask (measuring flask or graduated flask) is calibrated to contain a precise volume at a certain temperature. Volumetric flasks are used for precise dilutions and preparation of standard solutions. These flasks are usually pear shaped with a flat bottom and made of glass or plastic. The flask’s mouth is either furnished with a polyethylene stopper. The marking indicates the volume of liquid contained when filled up to that point. The marking is typically calibrated to contain (marked TC) at 20C degrees and indicated correspondingly on a label. Compliance with DIN ISO 1042 Standard.