The following description was prepared by William Gross:
Breastplates – ornamental metal plates or shields hung in front of the Torah scroll – are found in all Ashkenazi communities, as well as Italy and Turkey, but designed differently in each community. In most cases, the breastplate is made of silver or silver-plated metal. In Italy, the breastplate is shaped like a half-coronet and known as the Chatzi-keter, "half-crown." In Turkey, the breastplate is called a Tas, and assumes a variety of shapes – circular, triangular, oval, or even the Star of David. In Western, Central, and Eastern Europe the breastplate is called either Tas or ẓiẓ; its function there is not merely ornamental: it designates which Torah scroll is to be used for the Torah reading on any particular occasion, with interchangeable plaques.
The most notable early breastplates, from 17th-century Germany and Holland, were either square or rectangular, but over time they became rounded and decorative, and bells or small dedicatory plaques were suspended from its lower edge. During this period, the design of breastplates was influenced by that of the Torah Ark and the parokhet (curtain) concealing it, featuring various architectural motifs, the menorah (the seven-branched candelabrum), Moses and Aaron, lions, or Torah crowns.
Few Torah shields are as large as this one. The width and height are greater than normal and the three hanging medallions give an impression of even greater size. The workmanship is of fine quality, but there are no marks. Since the quality is of a fine German level but the form and broad conception are more suitable to the east, the Torah shield probably originates in the area that was subject to both influences -- Silesia. In Glogau there were Jewish silversmiths, but they were not allowed to put their marks on Jewish ritual art. This shield may be from that city. The area around Breslau, also in Silesia, gave birth in the 18th century to the Torah shield with figures of Moses and Aaron, as on this one. At the top are rendered the circumcision tools of the knife and the powder flask, indicating that this Torah shield was donated by a Mohel. Only one of the three medallions is original, that with the dating. The inscription on the others would have indicated the donor and perhaps the place.
On central plaque at the bottom: And Put it Upon Joseph's Hand...(Genesis 41:42), According to the Minor Reckoning (chronogram (5)536 = 1776)