The first all transistor hearing aids appeared in 1953. They were created to replace vacuum tubes; they were small, required less battery power and had less distortion and heat than their predecessor. The vacuum tubes were typically hot and fragile, so the transistor was the ideal replacement. The size of these transistors led to developments in miniature, carbon microphones. These microphones could be mounted on various items. There were body hearing aids where the earpiece was connected to the hearing aid and battery pack worn on the body. Ear level hearing aids consisted of eyeglass, behind the ear (BTE), in the ear (ITE), and in the canal (ITC, CIC) hearing aids. Part of the development of hearing aids Gold and burgundy metal casing, with an ear piece attached by wire. This is a body-worn hearing aid, with user instruction booklet. Manufactured by Rexton a subsidiary of Siemens."647 IV" on bottom of case, along with controls, "H N L" "M T O" and a numbered dial deaf children australia, hearing aid, rexton, siemens