A watch winder is a device used to keep automatic (also known as self winding) watches running when not worn. Automatic watches operate on the principle of winding themselves using a moving weight inside the watch. The weight swings or rotates while the watch is worn and turns the winding mechanism inside the watch. So, fairly obviously, if the watch is not worn, then it no longer receives power this way and will run down. While virtually all automatic watches can be manually wound, this is not always convenient. So the concept of an automatic watch winder was born. A watch winder is a device which holds a watch (or often more than one) and moves it in a circular patterns to emulate the necessary parts of human motion to operate the self-winding mechanism. A winder cannot over wind an automatic watch, since all automatic watches are protected from being over wound by a mechanism that disengages the winding process when the mainspring is fully wound. But using a timer-based winder is still very important to prevent excessive wear on the winding mechanism. There is no need to keep the watch in motion 24 hours a day when usually only 30 minutes of motion is necessary to keep it properly wound. Winders are totally useless with battery-operated quartz watches. But they do work for the special 'battery-less' quartz watches, such as the Omega-Matic, Seiko Kinetic, and similar. These automatic/quartz hybrids use the same weight/rotor principal to generate electric power to run a quartz movement.