Welcome to our shop! This infrared detector is designed to emit a switching signal through the built-in relay operation. When the emitted infrared beam is blocked, the relay will send a switching signal, and you can set the signal to normally open or normally closed. With its small volume, this detector can detect objects up to a maximum distance of 20 meters. It has extensive applications and can be used for road gates, automatic doors, mechanical operation safety protection, access control, security systems, and more. During installation, it is recommended to first install the receiver and then the transmitter. Make sure they are in the same horizontal line. When the installation is complete, the OFF light in the receiver should be off. Connect the wires and fix the devices. Please note that the installation height should be more than 20cm, and the distance between the transmitter and the receiver should be no less than 2m. The infrared protection device should be placed vertically and on the same horizontal line. This item includes 1 Transmitter, 1 Receiver, 1 Screw Accessories Package, and 1 English Manual. 100% Satisfaction: Our customers are our top priority. If you find any product problems after receiving the goods, such as damage and incorrect quantity of goods, please contact the seller immediately. We try our best to provide you with satisfactory after-sales service.