Pipettes are used for precise measurement and decanting of liquids. Graduated pipettes allow different amounts of liquid to be absorbed and dispensed in the same or in different sizes. Adjustment is made to drain ("Ex") for + 20 °C reference temperature. The tolerances for the volume content of calibratable pipettes correspond to the error limits of the German weights and measures regulations as well as ISO and DIN. The pipettes are made of soda-lime glass and comply with Class AS, waiting time 15 seconds. The scale is provided with main point ring division and the numbering takes place from top to bottom (drain-out). Pipettes with a batch number and accuracy Class AS are supplied with a batch certificate. This certificate documents the mean value obtained from measuring the batch in question, the standard deviation and the day of issue. The batch certificates can also be retrieved online. The batch number consists of four digits. The first two numbers specify the production year, and the following two numbers specify the batch, e.g.: 18.01.