Pushers are control elements on a watch that allow the user to activate or adjust peripheral functions of the base movement. They are typically located around the circumference of the watch case, similar to the crown. The head of a pusher is prominent and can be actuated with a simple press of the finger, with an integrated spring returning it to its initial position. Pushers are commonly used to operate mechanisms such as chronographs or to change time zones. They can be screwed onto their tubes to enhance waterproofing and prevent unintentional operation. Pushers operate in a linear, non-rotational motion and can have various shapes, including round, rectangular, or oval. The visible part of a pusher can be made from a variety of materials, often coordinated or contrasted with the case material, while the non-visible components are typically made from materials like steel or gold. The use of pushers became widespread with the advent of chronographs in the late 18th and early 19th centuries, and waterproof pushers were developed in the 20th century.