Specifications:

• Microphone: digital silicone mic
• Input voltage: 5V
• Battery capacity: microphone: 70mAh (2pcs=140mAh); charging bin: 600mAh
• Working time: about 6h
• Signal-to-noise ratio: 64DBM adaptive noise reduction
• Transmission delay: 30MS
• Sensitivity: -42DB
• Frequency response range: 20-20KHZ
• Transmission distance: 20m