Main based: 10k photo-resistance Measures the environment light intensity and input data Small size and easy handle One can detect the light intensity of the surrounding environment, Operating voltage 3.3V-5V Output form of digital switch output high and low (0 and 1) with fixed bolt hole for easy installation board PCB size: 3.4cm * 1.6cm The VCC external 3.3V-5V voltage (directly connected to the 5v microcontroller and 3.3v microcontroller