1These insert nuts are made from high quantity zinc plated carbon steel for durability and rust protection 2Screw-in insert nuts have an external thread and hex socket drive and are screwed in with a hex key wrench 3Insert nuts are advantageous over barrel nuts and T-nuts, because they can be installed from one side of the workpiece 4There are screw-in insert nuts in different sizes and take different screw sizes that you can choose for your project 5The pre-drilled hole must be as deep as the length of the insert nut plus any portion of the bolt that may be screwed past the end of the nut in the work piece