A volumetric flask (also called a graduated flask or measuring flask) is an apparatus calibrated to contain a highly precise volume of liquid at a certain temperature. They are used in precise dilutions and preparation of solutions.
Pear shaped, flat bottomed and made of glass, these flasks have an etched marking on their elongated neck. This is used to denote the specified volume of the flask at 20°C and is marked as ‘In’ or ‘TC’ (to contain) on the flask itself depending on brand and volume.