This is an under-counter mount for the Microsoft Surface power supply (power brick). It was created to hide the power brick and extra cable under my kitchen counter, as I have a Surface RT as my smarthome control touchscreen.
Although I haven't verified it, this should work for both the Surface RT and Surface Pro. There is just enough room for the brick, as well as some extra cable, keeping the box as small as possible.
Also see my Surface RT Wall Mount Frame at https://www.thingiverse.com/thing:3464072
4 small and short screws to attach to the underside of your counter