The ring is engraved on the outside with the initials of the names of the months, and has a small applied shield with a stag rampant. The shield is surrounded by the initials 'H G' and 'V B'. The sliding central band of the ring has the sighting hole. A hand and a star are engraved next to the sighting hole.
The hour numerals from 4 to 12 to 8 are engraved on the inside of the ring.
There is a smaller ring for suspension.
The instrument was formerly in the Franks Collection of finger rings (no. 1968), and is described in F. A. B. Ward, A Catalogue of European Scientific Instruments in the Department of Medieval and Later Antiquities of the British Museum (London, 1981), p. 62, no. 162.