Features: The wireless headset microphone adopts UHF band to signal interference at all times. Its signal transmission distance is up to 30 meters (without obstacle) 2.5ms transfer delay more reliable and stable for transmitting pure sound. A/B channel will the distraction of the same frequency by changing frequency when using the same frequency. (Channel A: 600~649MHz Channel B: 650~699MHz) The included receiver adopts 3.5mm audio plug which allows it to be directly plugged into any audio without connecting an output cable. Also provide a 6.35mm audio adapter. (can be directly plugged into the bus/car audio and outdoor draw-bar speakers etc.) Built-in 400mAh polymer lithium batteries in the headset microphone and the receiver. Battery runtime can be up to 5 hours. With low battery indicator and low battery shutdown function. With DC-5V USB charging port. The headset microphone and the receiver adopt the miniature design which are compact lightweight and portable. ABS+metal materials are dampproof and corrosion resistance. Can be used for teaching & training tour guide music playing KTV singing family entertainment conference hosting etc. Specifications: HEADSET MICROPHONE: Channel A: 600~649MHz Channel B: 650~699MHz Transmitted Power: 10dBM Capsule Type: Condenser Battery Type: 3.7V 400mAh lithium battery Size: 180 * 145 * 115mm / 7.09 * 5.71 * 4.53in RECEIVER: Channel A: 600~649MHz Channel B: 650~699MHz Frequency : 50Hz~15KHz Battery Type: 3.7V 400mAh lithium battery Size: 82 * 26mm / 3.23 * 1.02in Material: ABS Working Distance: 30m Item Weight: 81g / 2.88oz Package Weight: 219g / 7.75oz Package Size: 23.5 * 18.8 * 6.5cm / 9.25 * 7.40 * 2.56in Packing List: 1 * Headset Microphone 1 * Receiver 1 * USB Charging Cable 1 * 6.35mm Audio Adapter 1 * Manual (English)