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 to T-nuts, as they can be installed from one side of the room. MATCHING KIT: There are 6 different sizes of nuts (see detail size in description or photos) so so you can run 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 screwed in beyond the end of the nut into the workpiece.