1The user needs to configure an external audio system, K8 microphone supports multiple input connectors including USB audio input/HD Multimedia Interface input/optical input/3.5mm audio. 2The volume of the microphone and background song can be adjusted individually through the knob on the back. 3A professional wireless microphone system with 2 microphones,enjoy music with your friends provide a quality customer experience. 4With long transmission range approx 65.6in in open space, ensuring that can simultaneously without worrying about interferences. 5The microphone system is easy to use with multiple systems and is the perfect microphone system for any professional or entertainment activities. Item Type: Karaoke Box Material: Plastic + Metal Microphone Batteries: 2 x AA Batteries Per Microphone (Not Included) Voltage: 100-240V Frequency: 750MHz-769MHz Effective Distance: > Approx. 65.6in Frequency Response: 50Hz-17KHz Signal To Noise Ratio: > 100dB Distortion:1 x K8 Home Wireless Karaoke Box 2 x Wireless Microphone (not Including 1.5V AA x 2 Battery) 1 x DC USB Cable 1 xPower Adapter 1 x 3.5 MM Audio Cable 1 x 3.5MM to 2RCAJack Audio Cable 1 x Manual The microphone needs to be installed with two AA batteries before it can be used (batteries are not included in the )