2-Way Connectors by EZTube - EZTube | Easy to Assemble Aluminum Framing System
Multi-Way Tube Connectors for Square Tubes - Essentra Components
Steel Tube Connectors by Marni bemark, - Corner Joint 3 way Tube Connector (Galvanized) 25mm Tube Connectors are made of 2mm mild steel and is used on 25mm (1 inch) square tubing.