AV-JEFE AVL630 is one of the smallest and lightest professional headsets in the world. It is designed for lecturers, preachers, sportscasters, surveillance, stage performers and other applications requiring minimum microphone visibility with hands-free operation. Specifications: (1) Element: Back electret condenser (2) Polar Pattern: Omnidirectional (3) Frequency: 50Hz - 18,000 Hz (4) Sensitivity: -60dB ± 3dB (5) Impedance: 1,500 W ± 30% (6) Dimension: 5.2 x 144mm (7) Operation Range: 1V - 10V DC (8) Weight: 8 grams (without connector) (9) Connector: 3.5mm Locking Plug For use with your Sennheiser wireless body pack transmitters:Evolution Series, EW100, EW300, EW500, G1, G2, G3, SK1093, SK20, SK300. (10) Body pack transmitter NOT included.