This Vevor linear rail set includes four 39.4-inch 2040 T-slot aluminum extrusion profiles designed for DIY builds and machine framing. Made from 6063-T5 aluminum alloy with an anodized finish, the rails offer corrosion resistance and long-term durability. Precision-cut surfaces help provide smooth operation with reduced friction and reliable performance. The side groove design supports M4, M5, and M6 T-slot nuts for flexible assembly across many project types. Ideal applications include 3D printers, CNC machines, automation equipment, workbenches, and furniture projects.