The Stand Lock Plate attaches to the end of the 3.0″ square stand base extrusion end tapped holes. The 1.5″ square adjustable stand extrusion orients at a 45 degree angle to fit inside the 3.0″ square extrusion. Included with this plate is the handle kit to lock the adjusting extrusion and easily set the height, as well as the mounting hardware to the tapped holes in the 3.0″ square extrusion.