This ring dial comprises three rings (armillae). One ring is engraved on the outside with the names of the stars, and on the inside with the zodiac belt subdivided from 1 to 20 for the hours. There are two sights. Another ring carries on both sides a semi-circle divided into 90 degrees. A throne can be positioned in different ways depending on the latitude. There are hinges for closing the dial. Some characteristics suggest the instrument may have been made by Johannes Motter. Provenance: Medici collections.