Set includes: 3 different sizes of T-nuts packed in a durable clear plastic box, 50pcs M3, 50pcs M4, 50pcs M5, 150pcs in total, meet your different needs > Material: these nut fasteners are made of carbon steel, rust and corrosion resistant Thread diameter: diameter is 3mm (M3), 4mm (M4 ), 5mm (M5), 3 different sizes, each size 50 pieces Feature: T nuts are used to be inserted into aluminum frame and connected together with T screw or other Application: stainless steel nuts are suitable for 20 series aluminum profiles, widely applied to the construction of aluminum frame structures for industry, 3D printers, CNC laser cutters , robotics projects