Large PCB's require a mechanical stiffener to eliminate warp and bow which is often present. This is a must for good guidance of a PCB into an edge connector and for reliable operation afterward.
The typical construction for a PCB stiffener is a rectangular bar with drilled and tapped holes. Most PCB stiffeners are just that, but drilling and tapping holes in a bar is expensive. The Universal Stiffener, available for machine screw or rivet mounting, reduces this expense with design that will accept a screw or rivet anywhere along its length.