Vintage Aiwa HP-500 - Stereo Headphones - Boxed Made In Japan. Headphones are tested and fully working in excellent condition. Please see all photographs. Includes original box which had a crack in the front plastic but is otherwise in great condition. Dispatched with Royal Mail Special Delivery. HP500 - Aiwa Co. Ltd.; Tokyo HiFi headphones with Omni dynamic transduction system - all-round dynamic sound transducer system, frequency range: 15-25000Hz, impedance 16 ohms, 500mW. Net weight: 0.4kg Country: Japan ???????? Manufacturer / Brand: Aiwa Co. Ltd.; Tokyo Year: 1977 Impedance: 16 ohms Compatible Impedance: 4 ohms to 50 omhs. Frequency Response: 15 - 20,000Hz Max Nominal input: 500mW Output sound pressure level: 103dB/0.4mW Magnets: Ferrite Diaphragm material: 6 micron Polyester