The 3 hole - inside corner bracket is an external fastening method that creates a 90 degree connection. There are two stacked holes on one side and one hole on the opposite side of the bracket. This fastener requires no machining services and can provide infinite positioning along the profile T-slot, allowing a large degree of adjustability. The 3 hole - 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. The suggested mounting hardware can be found on the "Suggested Hardware" tab.