What do you think of the time in the perpetual calendar keychain?

Hang the perpetual calendar on the key chain and the key chain behind the door, so that you can see the time at any time when you go out. Perpetual calendars are all set with time. First, adjust the year to the day of the month, and then adjust other weeks, temperatures, solar terms and lunar calendar dates to Beijing time, which will be automatically generated and very accurate.