An insert nut provides a threaded socket for a wooden workpiece, similar to a wall anchor. These insert nuts are inserted into a pre-drilled hole by screw in, in that case the external protrusions bite into the wood, preventing the nut from either turning or pulling out. Features: These insert nuts are made from high quantity zinc plated carbon steel for durability and rust protection. Screw-in insert nuts have an external thread and hex socket drive and are screwed in with a hex key wrench. Insert nuts are advantageous over barrel nuts and T-nuts, because they can be installed from one side of the workpiece. There are screw-in insert nuts in different sizes and take different screw sizes that you can choose for your project. The 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. Specifications: Material: Zinc plated carbon steel Type: Hex socket screw-in Thread Type (pitch): Coarse thread Size and Quantity(Optional): M6*10mm 20pcs M6*13mm 20pcs M6*15mm 20pcs M6*17mm 20pcs M6*20mm 20pcs M6*25mm 20pcs M8*13mm 20pcs M8*15mm 20pcs M8*17mm 20pcs M8*20mm 20pcs M8*25mm 20pcs M10*25mm 20pcs Package Includes: 20pcs x Insert Nuts .