GREAT QUALITY: These insert nuts are made from high quantity zinc plated carbon steel material which provides strength and good corrosion resistance in many environments. EASY TO USE : They are versatile threaded insert nuts that you can easily drive with them, easy to use. FEATURES: Insert nuts are advantageous over cylindrical nuts and T-nuts, as they can be installed in one side of the piece. MATCHING KIT: There are 6 different sizes of nuts (see detail size in description or photos) so you can manage your project for free. NOTE: The pre-drilled hole should be as deep as the length of the insert nut and any part of the bolt that can be threaded past the end of the nut into the workpiece. Size and quantity (optional): M6 * 10 mm 20 pcs (optional) M6 * 13mm 20 pcs (optional) M6 * 15mm 20 pcs (optional) M6 * 17mm 20 pcs (optional) M6 * 20mm 20 pcs (optional) M6 * 25mm 20 pcs (optional) M8 * 13mm 20 pcs (optional) M8 * 15mm 20 pcs (optional ) M8 * 17mm 20 pcs (optional) M8 * 20mm 20