The SmartiPi Touch 2 back cover screws into the four brass threaded insert holes on the back of the SmartiPi Touch 2. It creates a 15mm deep open area behind the SmartiPi Touch 2 in which you can add your own electronics. It is made out of ABS plastic. There are no mounting holes on the inside of the cover. If you want to use this cover with the fan door part of it will need to be removed so it will fit.