Product information: Name: wireless microphone Model: K35 Type: Computer Karaoke Microphone, Professional Recording Microphone, Built-in Audio Microphone. Material: ABS + electronic components Color:Black Specifications: one for two Bluetooth Version: 5.1 Frequency range: 2.4G Charging input voltage: 4.8V-5.4V Working time: about 4 hours Charging interface: TYPE-C Battery capacity: 40mAh Working temperature: -10~45 degree Starting current: 10-11 ma Transmission delay: 30 ms Sensitivity (mic): -42db Frequency response: 20-20KHz Transmission distance: straight line 20 meters, obstacles about 7 meters. Applicable objects: home, computer, stage, dedicated to cameras, dedicated to recording, musical instruments, dedicated to radio and television, dedicated to ktv, dedicated to conferences, dedicated to interviews and live broadcast crowds .