50 YEARS PERPETUAL CALENDAR & COMPASS

HOW TO USE:
Turn the upper disc, aligning the year and month you want to seek, then the diagonal direction will show you the week information of each day in the month
You can know the week of every day in the range of 2007-2056
Black “S” means Saturday and red “S” means Sunday
When you seek for January or February in a leap year, you should aligning with the red “JAN” and “FEB”