Features: UHF technology with low power consumption, high anti-interference capability, and use distance up to 40m(without obstacle). Frequency modulation; Up to 40 units can be used simultaneously without crosstalk or interference. Condenser microphone, high sensitivity, clear vocal. Built-in 400mAh Li-ion battery lasts for 6h operation. Suitable for use with amplifiers or speakers in speech, teaching, tour guide, promotional activities, etc. Specifications: Material: ABS Frequency Response: 60Hz-16KHz Frequency Range: 630MHz-890MHz Operation Voltage: DC2.5-5.5V Battery: Li-ion battery 400mAh Charging Voltage: DC 5V-200mA Charging Time: approximate 2.5h Operation Time: 6h Sensitivity: -51~-54dB Operation Range: about 40m in open area Net Weight: Receiver: 23g, Headworn microphone: 38g Item Size: 80 * 28 * 15mm / 3.15 * 1.10 * 0.59in Package Weight: 142g / 5.02oz Package Size: 18.5 * 14.5 * 4cm / 7.28 * 5.71 * 1.57in Package List: 1 * Headworn Microphone 1 * Receiver 1 * Charging Cable 1 * Manual (English)