photosensitive resistance module's most sensitive to ambient light, commonly used to detect environment around the brightness of the light, or MCU trigger relay module, etc. module in the environment light intensity than set threshold, output high level DO end, when the environment light intensity more than set threshold, the DO output low level the DO output can be directly connected to microcontroller, through single chip microcomputer to detect the high and low level, thus to detect the environment light intensity change the DO output can be directly our relay module, which can form a light-operated switch. Colour:As Shown Material:plastic Package Contents: 10 * for light sensor 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.