The Revolution and RXL have open bottom corners in the frame - some of which have wires passing through, others are unused. This part is designed to fit snugly in one of those open corners, and can be used as a starting point for more specialized parts like my "Corner Bracket with Rocker Switch Insert". Designed to be printed without supports - just slide the small snap-in piece into the larger main body piece. Individual STL files provided as well as pre-sliced GCODE that should work reliably well for brand-new RXL/Revolution printers right out of the box.