Rechargeable Microphone: No need to purchase additional AA batteries. Microphone and receiver are built-in 1200mAh rechargeable lithium-ion battery. Working time up to 7 hours plus with charging time of 3 to 4 hours. Charging cable is included in the package, supports charging the dual microphones and receiver in one cable at the same time. Cool LED ring light (runs in green, charges in red) and an upgraded clear white LED display. UHF Wireless Microphone (Pro): The microphone adopts UHF frequency band (use legal signal bands with US FCC ID), open place: UHF distance 240ft/75m, signal stability. Receiver with Bluetooth, or as a Bluetooth receiver to play music on old speakers. Turn on the receiver, search the Bluetooth name: Bietrun, play your karaoke music. Bluetooth(10m). Dynamic Vocal Microphone: Built-in dynamic unidirectional microphone core (dB value: 95dB/Audio signal: 48Khz/Frequency response: 50Hz - 16Khz), Vocal built-in boost circuit design is clearer. The o