PREMIUM QUALITY: These insert nuts are made of high quality galvanized carbon steel material, which provides strength and good corrosion resistance in many environments. Easy to Use: These are multifunctional threaded nuts, you can easily drive with them, easy to use. Features: Insert nuts have advantages over barrel nuts and T-nuts because they can be installed on one side of the workpiece. Note: The depth of the pre-drilled hole should be the same as the length of any part of the embedded nut and bolt that can be screwed through the end of the nut into the workpiece.