DS18 DS-MIC318 Wireless Lavalier Microphone Wireless Lavalier microphone Microphone Sensitivity: -72dB, Directivity: Uni-Directional Frequency Response: 100 Hz - 10 KHz, Output Impedance: 600Ohms Operating Voltage: 1.5V or 9V DC, Effective Distance: 50 - 100 Feet Parts Included: 1 Receiver Module, 1 Lapel (Lavallier) microphone, 1 Transmitter, and 2 Batteries