Instructions for use: circular perpetual calendar.

You have to match year and month. In other words: Place year over month.

The years in red are leap years. The months in red are for leap years. In case you want to consult a leap year but there is no red month available, use the black month.

These instructions will be useful for articles:

Brass perpetual calendar, rudder wheel Ø14cm

Brass perpetual calendar Ø9cm