Features: light & portable. Noiseless (-58d B) microphone with Omni directional capacitance electret. Equipped with the volume control. Adjustable headband for comfort Adjustable microphone Specifications Driver Unit: & Ouml;30mm Speaker Impedance: 32ohm±15% Speaker Sensitivity: 97d B±3d B Speaker Frequency Response: 20-20, 000 Hz Maximum Power Input: 40mw Microphone Operating Voltage: 4.5V Microphone impedance: 2.2 K Microphone sensitivity: -58d B±2d B Microphone Frequency Response: 30-16, 000 Hz Cord Length: 2.2 meters