Bluetooth for Mission Critical Wireless Bluetooth for Two Way Radio. No Words Missing and High Reliability. 10-hour Talking Time. Campatiable with Third Party Bluetooth kit. Working with Various Professional Earphones. Convenient Volume Control for Better Hearing Protection. Specification Compliance Bluetooth V1.2, CLASS 2 (1.0mW) Talk Time10hrs Range10m Dongle Dimension66*35*16mm PTT Dimension60*20*14mm BatteryDongle: 400mAh Headset: 300mAh Microphone TypeElectret Condenser Microphone Impedance 2.2kOhm Sensitivity-40±3dB at 1000Hz(0dB=1V/Pa) Operating voltage1.0-10VDC