Connection Screws are an inexpensive connection method that facilitates a fast assembly. An access hole is required at the connection point of the joining piece of extrusion in order to tighten the connection screw in place. To fasten, the connection screw is inserted into the tapped end of an extrusion. Next, the head of the screw slides into the T-slot of the joining piece of extrusion until it is visible through the access hole. Then simply tighten the screw with a screwdriver or hex wrench through the access hole. The butterfly clip prevents the extrusion from twisting out of place.