The PCB heat bed is a great addition to your 3D printer to help your printing platform to be a heated surface perfect for minimizing warping of larger prints. The heating element is on the bottom side. The heating is done by long traces of copper. The top side is solid copper to keep the PCB flat enough.     The Aluminium Bed Mount Plate design is pre-drilled and tapped to mount boltable bushings, the PCB heated print bed, belt standoffs, belt clamps. MK2a is the latest and the best type of heatbed money can buy as of today. 100% compatible with all Prusa and Mendel 3d printer variants. You can also know more about Mk2A here.