The Sony ECM-22P is a classic cardioid condenser type with uniform response from 40 to 15,000 Hz. The capsule is 17 mm in diameter and made of a high-polymer film utilizing the electret principle of polarization and two output impedances: 250 or 600 ohms can be selected by changing the impedance switch. The ECM-22P can be operated on an external DC power supply without any additional conductors or cables, besides battery operation. The microphone does not have a battery included in it and has a loose, possibly broken, switch on it. This unit has not been tested and may not function, for parts or project only. Owned and used by the famous Indigo Ranch Studios.