The first ever Grand Seiko chronograph, this model is powered by a Grand Seiko exclusive spring-loaded caliber, which combines the driving force of a mainspring with the high precision of a quartz watch. The spring-loaded mechanism allows the watch to maintain accurate timekeeping, while complementing the accurate capabilities of a chronograph, all with a maximum power reserve of 72 hours (3 days). The original Grand Seiko sliding movement is also present in the blue steel second hand of the chronograph. The chronograph uses a Ready / Start button with a half-press shutter, reducing errors and enabling accurate starts. The button has been designed with comfort of use in mind and produces a satisfying click with just the right resistance.