The 4 hole - tall gusseted inside corner bracket is a strong, external fastening method that creates a 90 degree connection. Each side of the bracket has two holes stacked one on top of the other. It requires no machining services and can provide infinite positioning along the profile T-slot, allowing a large degree of adjustability. The shape of the gusset provides extra material, strengthening the connection. The 4 hole - tall gusseted inside corner bracket engages the 2-degree drop-lock feature when the assembly bolts are tightened to the required torque. It is a fastening method that can be repositioned and reused.