Outflow cups are still the most important measuring instruments for determining the consistency of liquids, in a simple and fast manner, within the laboratory and in production. However, they are only suitable for low-viscosity liquids, and not for high-viscosity substances such as pastes. The most accurate results are achieved in liquids with Newtonian behaviours. The outflow cups themselves are made of anodized aluminium, while the nozzles are generally made of stainless steel. ISO 2431, DIN EN ISO 2431.