1. Worried about unstable signal at short distance? You can add multiple controllers to learn configuration and automatically relay network. You can configure multiple relays to achieve ultra-long-distance linkage control. 2. Active input is converted to passive input. The input of the controller is a passive dry contact and cannot be energized. Passive input can be achieved through intermediate relay conversion. 3. Collect the output status, collect the output status, feedback to the input end, and remotely view the equipment operation status. 4. Dial-up frequency modulation does not interfere with each other. More than 16 channels can be , so there is no need to worry about local frequency conflicts. Working frequency band: 410 - 490MHz Transmission distance: 5000m (open space) Colour: Material:ABS Package Contents: 1 set x LORA Wireless Intercom Switch Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.