Package Content: 12 pcs 20mm 90 Degree Solid Cast Aluminum Corner Bracket,24 pcs Carbon Steel Galvanized M5 T-slot Nuts, 24 pcs Carbon steel M5 Hex Socket Cap Screw Bolt, 1 piece wrench. 20 × 28 × 28mm(0.78″x1.1″x1.1″) Aluminum Corner Bracket used to connect pieces of 20mm aluminum extrusion at a 90 degree angle Suitable for most of metric 20mm x 20mm series aluminum extrusion profile rail. Hex Socket Button Head Bolts Screws Nuts Surface chrome finish Anti-corrosion,rustless,non-pollution. T-Slot Aluminum Extrusion M5x8mm Hardware Slide In T-Nuts made from high quality carbon steel Galvanized. 2020 Series Aluminum Profile Connector Set widely used for building industrial aluminum frame structures, 3D printers, CNC Routers, CNC laser cutters, Robotics Projects.