A pencil jet nozzle is a type of pressure washer accessory that directs the water stream into a single, thin, and very powerful jet. Thanks to this concentration of energy on a very small area, the jet achieves a high cleaning effect. It is used to remove extremely stubborn and localized dirt, such as dried mud deposits, weeds and moss in paving joints, or stains on concrete. However, its force is so great that it can damage more delicate materials, such as wood, car paint, or facades, and is therefore intended for work on very hard and durable surfaces. It is sometimes referred to as a '0-degree nozzle' because the water spray angle is practically zero.