High Quality: These insert nuts are made of zinc plated carbon steel, giving them great strength and good corrosion resistance in many environments. . Easy to Use: These are multi-purpose threaded insert nuts, easy for you to assemble, easy to use. . Features: Insert nuts are advantageous over straight nuts and T-slots because they can be installed from one side of the part. . Matching Set: There are 6 different size insert nuts (please see the detailed size in the description or pictures), so you can edit your project for free. . Note: The pre-drilled hole should be as deep as the length of the nut to be inserted plus a portion of the bolt that can be threaded onto the end of the nut in space. Translated by www.DeepL. com/Translator (free version)