This perpetual calendar can hang year after year. Sliding rings are changed daily to show the current day, date, and month. A simple hook on the back allows for the calendar to be hung and taken down as needed. There are no mechanisms involved, the rings are braced in place with friction and a precise fit. *It takes a little practice to get the hang of moving the rings, but once you’ve got it, it’s easy. This design measures 7.5″ across.