HC-7D sensor switch can detect the infrared Rays released by human body motion within theDetection area, then start the load-light automatically. This unit is suitable for outdoor use.
This PIR Sensor has an extra feature of manual override. IS9D has a longer detection range and wider angle, it is better for security use.
Many customers like to install the HC-7D in the garden, because it has an overridden function. IS9D can load higher watts, so the sensor is suitable for outdoor.