This device attaches to a WorkPro Desk (WORKPRO 48" Adjustable Workbench, Rubber Wood Top Heavy-Duty Workstation, 2000 LBS Load Capacity Hardwood Worktable with Power Outlets, for Workshop, Garage - Amazon.com) in order to extend it about 3".  I built this so my A1 enclosure would be supported on the back of the desk.  It takes several of these to achieve your desired width. Each piece has holes for two screws to attach to the underside of the desk.