"Fortiphone" battery hearing aid, cased, by Siemens and Halske, Berlin, 1900-1940 "Fortiphone" battery hearing aid 1900-1940
"Duchess" electrical hearing aid, cased, English, 1950-1970 "Duchess" electrical hearing aid 1950-1970
"Fortiphone 30A" electrical hearing aid, cased, by Fortiphone, London, 1945-1960 "Fortiphone 30A" electrical hearing aid 1945-1960
Medresco battery hearing aid with leather case, English, 1950-1965 Medresco battery hearing aid with leather case