Excellent Quality: These nuts are made of high quality zinc plated carbon steel which provides strength and good corrosion resistance in many environments. Easy to Use: These versatile threaded nuts will help you make them easy to use, easy to use. Features: Insert nuts are advantageous over cylindrical nuts and T-nuts because they can be installed from one side of the part.< /p> Matched Kit: There are 6 different sizes of nuts (please see size details in description or photos) so you can handle your project for free. Note: the pre-drilled hole should be as deep as the length of the insert nut plus any part of the bolt that can be screwed past the end of the nut into the work piece