High To Low Impedance Adapter (General Aviation GA To Military)Twin Jack to Military Headset adapter converts a general aviation headset for use in a Military Aircraft. It converts the plugs as well as the High-Impedance Mic (used in General Aviation) to Low-Impedance for use in Military aircraft. Requires one 9 volt battery. This allows you to use a G.A. Headset in a Military Aircraft. Two female G.A. Jacks: .250? Headphone (PJ-055) and .206? Microphone (PJ-068) One Military Plug (U-174/U)