1. Hands free two-way talkback full automatic. 2. Clear sound .High-quality speaker and high-sensitive microphone, the voice is realistic and clear 3. Reminder light.There are voice transmission indicator to prompt the working condition 4. with volume knob. the volume of internal and external can be adjusted . 5. With power on /off knob 6. High power;3W high power speaker, widely used in many applications, such as bank, clinic, government，store, pharmacy, and so on Technical Parameters: Working voltage: DC12V Material : High quality ABS Working current: ≤300mA Microphone : 45dB±2dB 10Hz-15KHz Output power of sub-base Speaker: 3W Output power of master:2W Environment term: -10oC~60oC Cable Length : 2M, silver Main base :148*98*33mm Sub-base: 80*22mm Box size :  21*13*8CM