New open box 🎤 Rechargeable & LED Display : Microphones receiver can be rechargeable. No need to set! No need to buy batteries! The microphones can last for about 30 hrs, the receiver's battery can last for 15 hrs.With dual USB charging port for charging. The microphones display can show the battery power and signal strength in real time, don't worry about suddenly not working. 🎤 Easy to Use : Plug and play, no need https://offerup.co/faYXKzQFnY?$deeplink_path=/redirect/ need to buy batteries! The receiving box adopts 6.35mm audio head, which can be directly plugged into any audio (especially perfect for Karaoke, Speech, Meeting, Performance, Indoor or Outdoor. Design for Outdoor Karaoke Speaker, PA Speaker System, Power Amplifier, etc), no need to connect the output line separately.( NOT for Bluetooth Speakers/PC/Phones) 🎤 Variable Channels: Support 4 sets at max for simultaneously using in the same area,(Each Set Using In Different Channel), avoiding interference signals at any time. The international standard working distance is 15 meters (measured 30 meters).NOTE: If Microphone & Receiver can’t connect with each other, they need Pairing to Reset, please see how to Pair/Reset in Product Picture, Product Description or User Manual. 🎤 Advanced Technology : Microphone & Receiver use advanced connection technology, Indoor range >50ft(Outdoor range >100ft); Frequency Response 50Hz-18kHz; SNR >70dB; Distortion <0.5%; Latency <3ms. 🎤 High-Quality Materials : The dual microphone adopts metal aluminum tube, and the net head is made of metal baking varnish, which is safe and fall-proof and durable.The receiving box is directly plugged into the stereo and it is portable.