Pipettes are widely and frequently used in chemistry, biotechnology, microbiology and biology laboratories to transfer liquids accurately and safely. Plastic pipettes come in various shapes and to serve different functions. Plastic Pasteur pipettes have a bulb-shaped top and are shorter, as they are designed for small volumes and counting drops. Serological pipettes can accommodate higher volumes and feature double graduation with one positive and one negative (or inverted) scale. For safety reasons, they should always be used with a manual aspirator or automatic pipette. There is a wide range of automatic pipettes that can be used to adjust the exact volume to be dispensed. Additionally, they must be used with single-use pipette tips. Glass pipettes can be found in the subsection on volumetric materials within the glassware and quartz section.