Easy managing of the time is the aim of this watch. I want to quickly and visualy answer simple questions as "How much time remaining if take off is at 16H45 ? " The external 24 hours ring turns with time. Inner ring is used to see quickly remaining time/target time. Dark blue ring is aeronautical night (sr-30 to ss+30), cyan is night (sr to ss), yellow is day. Battery will flash below 30%. To switch screens, double tap on center. After 2 minutes it will go back to default screen witch is timer. More instructions in watch instructions. Feel free to comment. https://plus.google.com/110031606388059336149/posts/HsJfUA65w7i FLY SAFE