The Seiko Y643-0100 watch movement features a pointed balance staff equipped with white jewels. Additionally, it incorporates a diode parallel to the inductor on the balance to stabilize amplitude and enhance durability by preventing sparks at the contact. The movement includes several functions such as an electromechanically controlled balance motor, sweep second hand, date setting within a range of +/-24 hours, and a hack feature. The M51 movement was commonly utilized around 1975.