Basic size: 40mmx40mm; for aluminum profile 4040 seriesFlexible Pivot Joint Connector, used to connect pieces of 40mm aluminum extrusion with any degree, free adjust, Then fixedConvenient to use, they can be simply fastened with bolts and nuts, (bolts and nuts are not included)4040 Series Aluminum Profile Connector widely used for building industrial aluminum frame structures, 3D printers, CNC Routers, CNC laser-cutters, Robotics Projectscolour:SilverMaterial:MetalPackage Contents:1 x Flexible Pivot Joint ConnectorOnly the above package content, other products are not included.Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.