This MKS Filament Runout Sensor interfaces with your motherboard and Marlin to tell your printer when it has run out of filament or not.
So easy to install on my MKS Gen-L V1.0 Controller Board. it required a quick firmware flash to recognize the sensor (I have my Marlin Tevo Tornado firmware saved so I can do this) and plug into the board and I was up and running.
I just printed a mount for my printer off of Thingiverse to complete the set up. This sensor is very useful for long overnight prints or prints where your older filament is getting a bit brittle and you are trying to finish a roll.
Super easy install with a bit of techinical knowledge. Again lots of very good help on Youtube etc.