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 allow you to use them easily, easy to use. Features: Insert nuts are advantageous over barrel nuts and T-nuts because they can be installed from one side of the workpiece. Assorted Kit: There are 6 different sizes of nuts (please see the size details in the description or pictures) so that 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 workpiece. Product Description Size and Quantity(optional): M6*10mm 20pcs(optional) M6*13mm 20pcs(optional) M6*15mm 20pcs(optional) M6*17mm 20pcs(optional) M6*20mm 20pcs(optional) M6*25mm 20pcs(optional) M8*13mm 20pcs(optional) M8*15mm 20pcs(optional) M8*17mm 20pcs(optional) M8*20mm 20pcs(optional) M8*25mm