Features: 1. The transmitter is integrated with the function of AC/DC voltmeter, which can measure 12 to 400V AC/DC voltage on a linear basis. 2. The screen of the transmitter can display preset transmitting power, transmitted codes-its own battery energy-mains voltage detected-AC/DC status of mains voltage detected-and warning symbol for mains voltage. 3. The Transmitter has the function of self-inspection to detect its own working status and to display it on the LCD screen for user's reference 4. The sensitivity of the receiver can be adjusted either manually or automatically 5. The receiver can sweep frequency automatically 6. Both the transmitter and the receiver can work under mute mode 7. Additional transmitters are available to extende or distinguish multiple signals. 8. Compactness-durability and portability 9. Auto power off within 10 minutes. 10. Flashlight Function. 11. Backlight Function. 12. Mute Function.