Use on 20mm x 20mm Extrusion Profile, 2020 Series Aluminum Profile Connector Set widely used for building industrial aluminum frame structures, 3D printers, CNC Routers, CNC laser cutters, Robotics Projects. Aluminum Corner Bracket used to connect pieces of 20mm aluminum extrusion at a 90 degree angle suitable for most of metric 20 Series Aluminum Profile Extrusion.