Seiko Men's Watches Premier SNP005P - WW Once set, the calendar automatically adjusts for odd and even months including February of leap years up to February 28, 2100 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's been asleep for up to four years. Window indicates the number years since the last leap year,High Accuracy - monthly loss/gain rate of 15 seconds,Oversized dual date windows 24-hour and 12-month subdials, Energy depletion forewarning function, Cabochon crown Sapphire crystal, LumiBrite Hands & Markers, Water resistant up to 100M