Parameters Silicon wheat type: electret capacitor mark Sampling rate: 32KHz Transmission frequency: 2.4GHz Frequency range: 20Hz-20KHz Transmission time: 20ms Battery capacity: 400mAh Charging time: about 170min Working hours: 24 hours Transmission distance: 50 meters (without obstacles) Product color: black 3-in-1 Receiver: Lightning/TYPE-C/3.5mm port Transmission frequency: 2.4GHz Frequency range: 20Hz-20KHz Battery capacity: 320mAh (with protection board) Working hours: 20h