GREAT QUALITY: These insert nuts are made from high quantity zinc plated carbon steel material which provides strength and offers 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 barrel nuts and T-nuts because they can be installed from one side of the part. MATCHING KIT: There are different sizes of nuts (see detail size in description or photos) so you can handle your project for free. NOTE: The pre-drilled hole must be as deep as the length of the insert nut and any part of the bolt that can be screwed past the end of the nut into the workpiece. Size and quantity (optional): M610mm 20 pcs (optional) M613mm 20 pcs(optional) M615mm 20 pcs(optional) M617mm 20 pcs(optional) M620mm 20 pcs(optional) M625mm 20 pcs(optional) M813mm 20 pcs(optional) M815mm 20 pcs(optional ) M817mm 20 pcs(optional) M820mm 20 pcs(optional) M8*25mm 20