Seiko Premier Kinetic Perpetual Calendar SNP021P1 SNP021 SNP021PPerpetual Calendar with leap year correct until February 28, 2100. Time relay system preserves accurate time for up to 4 years. When the watch senses 24 hours of inactivity, it puts itself into suspended animation (sleep mode) to conserve energy. The date continues to advance correctly while the watch is asleep. Wake it up with a few shakes of your wrist and it automatically resets itself to the correct time even if it has been asleep for up to 4 Years.