The top of the instrument is marked (translated from German) "P. Semerak - Institute for Therapeutical Cosmetic and Massage, Niederloessnitz near Dresden". The letters D.R.G.M stand for "Deutsches Reichsgebrauchsmuster" or registered utility patent of the Deutsches Reich and this is found on many all German products produced between 1891 and 1949. Often referred to as "the patent of the ordinary man" it gave patent protection for 10 years. The massager would have been made between 1891 and 1923, after which the town Niederlössnitz near Dresden was renamed "Kötzschenbroda". (Thanks to Timo Rybicki for this information). The body is made from two flat pieces of wood over which a plated metal frame has been secured. The underside shows the internal mechanism. Rubber hammers attached to steel springs are made taught and released by the turning of 5 wooden wheels. When the wheels are run over an area of skin the subject experiences a pummeling from each of the four rubber hammers in turn. The force with which they strike can be adjusted by a screw at one end. Dimensions 65 x 70 x 150 mm.