The 18 hole - inside corner bracket is an external fastening method that creates a 90 degree connection. Each side of the bracket has nine holes comprised of three rows and three columns. This fastener requires no machining services and can provide infinite positioning along the profile T-slot, allowing a large degree of adjustability. The 18 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.