@AnoE Except, they can't be stacked, as many need top operation, but as well for weight. Some (like printers) need front or back access as well. This especially count for all CPU or controller frames, as they are not your average small scale 19" racks, but mainFRAME rack - 21" wide and a frame to be swung out like a gate in each side holding boards. They are not puny 1-4 HE elements that can be pulled out, but usually a contained group (like a memory block) is 1/2 of such a frame. Everything more dense packed than on a mini computer. – Raffzahn Jan 25 '19 at 12:31