Spring Drive is a technology unique to Seiko that combines the power derived from a mainspring with the high accuracy of a quartz crystal, making it possible to deliver the one-second-a-day precision that no other mechanical watches can achieve. After over 20 years of development, Spring Drive was introduced in 1999 as a revolutionary mechanism characterized by ultimate energy efficiency and the smooth glide motion of the second hand. Since the first Grand Seiko Spring Drive model was released in 2004, the fusion of cutting-edge technology with Japanese master artisanal skills has received international acclaim.