4. The one produced provides a self-control function for the sliding door. Once the self-test beam is interrupted, the door will stop closing and quickly retract to its maximum. The door will remain open until the detection beam is restored. When the door is completely closed, the detection beam is invalid 2. Can prevent interference from external light 1. Composed of a transmitter and receiver, the built-in amplifier can generate an infrared beam. 3. Even if installed at a lower one (20-40 cm from the ground), the detection distance (5-15 meters) can be guaranteed. 5. Used for automatic sliding doors, automatic doors, roll up doors, garage doors, windows, railings, Weight: 0.30644254418 pounds, Manufacturer: Faeymth