The back for the cover for SmartiPi Touch 2 allows you to cover HAT boards or other additional electronics on the back of the SmartiPi Touch 2 . The covers include four M4 mounting screws that attach the cover to the 75mm VESA mount holes on the back of the case. The cover does not work with the door or the fan door. You will have to modify it if you want it to work with the back door.
This is 15mm version. Dimensions are inside dimensions from the back of SmartiPi Touch. It is made out of ABS plastic.