"I played around with this sensor to automate my Lego Trains. It was pretty cool but the system has options (through the Powered Up App) to sense 9 colors (black, blue, green, yellow, red, white, purple, teal, and orange) as well no color. It really only senses 5 of these from what I can tell, none/black, green, yellow, red, and blue. The sensor has a light which is great 'cause if you put it under the trains (I put it in the new version of the cargo train by shifting backward the battery box) it won't have much light. It's really cool 'cause I can automate a lot of stuff with, but since it doesn't really sense the rest of the colors (even when changing the color of the sensor's light) it can't be used as precisely as I'd like. Still, it's not very expensive and the basic hub comes with enough ports for a train motor and a sensor so you don't need more equipment than the sensor to upgrade your setup."