This circular compendium is unusually small in size, with a diameter of just 43 mm and a depth of 13 mm. The instrument has a main drum and a cover, with a swivelling suspension ring. The outside of the drum is decorated with a band of wreath engraving.
With one exception, all of the inscriptions on the instrument are in Italian.
The top cover carries a nocturnal with a fixed calendar scale, each month divided to 10 and 2, and numbered by 10 (adjusted to the length of the month). The south point of the calendar scale (beside the hinge) is approximately February 16.
The volvelle has a scale of hours 3 to 12 to 9 with small projecting teeth. The volvelle is set against the calendar scale by a pointer marked 'A', placed in the middle of the cut away edge of the volvelle corresponding to the daylight hours. An inscription reads 'Quest indice col .A. ha da stare sul didel mezi'. The rotating rule, whose jointed outer part is a replacement, is marked 'B' and also has instructions provided: 'L'indice col .B. Quando e mezzo sul le due stelle posteriori dell Vrsa maggior il monstra l' hore della notte'.
The volvelle also has two apertures through which the times of sunrise and sunset are revealed for the latitudes 40, 43 and 46? (see also Epact 33741). The apertures are identified as 'l'orto del sole' and 'l'occaso del sole' and the latitude scales are marked 'l'eleuacio del polo'. The three hour scales revealed by the apertures are divided to 1/4 and numbered every 30 minutes. Values in minutes are given for the earliest and latest times of sunrise.
The reverse of the cover has a lunar volvelle. There is an outer scale of hours I to XII, I to XII and the silvered volvelle is cut away around a pointer marked 'C' to reveal a scale for the age of the moon 0 to 28 [291/2]. The volvelle is captioned 'INDEX .C. DIERVM AETATIS LVNAE' (the only inscription not in Italian) and its scale of hours runs 3 to 12 to 9. There is a circular aperture to reveal a diagram of the phases of the moon and an aspectarium with the symbols for conjunction, trine, quadrature and sextile.
Folding into the drum of the main box is a universal equinoctial sundial. It has a cross piece gnomon and a silvered hour ring 1 to 12, 1 to 12, around which is a sliding brass ring marked 1 to 24 for Italian hours. The underside of the hour ring is signed 'Horologio Generale Fatto monaco per maistro Vdalricus Schniepp anno . 1566 .'
The hour ring is set for latitude against a silvered folding arc with a scale of degrees for the pole's zenith distance 0 to 80, divided to 10, 5 and 1, and numbered by 10.
The main box contains a compass and wind rose. The compass bowl is 16 mm in diameter and its silvered base plate has a single arrow line to indicate the meridian. The wind rose gives the name of the eight Italian winds and the weather they bring. Set against the edge of the compass bowl in the portion for 'LEVECHO' is a scale of degrees 75 to 90 to 30, divided to 10 and 2, and numbered by 10.
The base of the instrument carries a circular table of the latitudes of 32 places titled 'l'eleuacio del polo artcicus'.