This is the latest revision of my mount to be able to upgrade a UMO+ with the UM2 Drivetrain Extrusion upgrade kit to be able to get the same feeder and printhead as the latest and greatest UM2+Prints without support on the top edge, or lying down with support. The long slot is for cable management, you put the whole bundle in there and fasten it with three zipties It should even be possible to use this to upgrade a non-plus UMO if you also get a PT100 amplifier board.