Product Information: Product Name: Socket Head Cap Screw Material: Iron Quantity: 230 pcs Surface Treatment: Galvanized Head type: hex headYou will get: 80 pieces 4 * 10mm 60 pieces 5 * 10mm 30 pieces 6 * 10mm 20 pieces 6 * 15mm 20 pieces 6 * 17mm 9 pieces 6 * 20mm 5 pieces 8 * 20mm 6 pieces 8 * 25mm Notes installation need to drill a small hole of suitable size with an electric drill, use a hex wrench to screw it into the hole. Then add 2-3mm of wood glue to the hole (on the side wall). Insert the nut and turn it several times, then deposit 2-3 mm of glue on the threads of the nut, then turn the nut 180 degrees. Please tighten the nut fully, After that, the nut will not loosen and is firmly connected to the wood. Note: The depth of the pre-drilled hole should be deep to the length of the inserted nut and the bolt can be turned beyond the depth of any part of the end of the nut.