Good Quality Zinc Alloy MaterialWood threaded insert is made of quality zinc alloy material, for durability and rust protection and long service life. Easy to UseThey are versatile threaded insert nuts that you can easily drive with them, Drill a suitable size hole and install it with a hex wrench, very simple. Unique AdvantagesBecause they can be installed from one side of the workpiece, wood screws are advantageous compared to barrel nuts and T-nuts. Reasonable DesignThe unique external thread design contributes to tapping, ensures strong pull-out resistance, prevents surfaces from splitting and causing the insertion to be too deep. Assorted KitThere are 7 different sizes of nuts, threaded inserts are stored in separate grids, allowing you to quickly select the ones you need. The hexagon socket screw inserts are made of good quality zinc alloy, hard and durable. The external thread designed for tapping, contributes to tapping, with good tensile strength, can effectively prevent detachment by twisting or vibration. There are 7 sizes to use (M4*10) 30pcs (M5*10) 30pcs (M6*10) 20pcs (M6*15) 20pcs (M8*15) 10pcs (M8*20) 10pcs (M10*25)10pcs Specification: box set Material: zinc alloy Color: copper Quantity: 130pcs Can be used for cork, plywood, fiberboard, etc. Package Contents: 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 +/-0-30mm. Thank you for your understanding.