English: A photograph showing two lag screws, also called lag bolts. The pen and the toothbrush are shown for scale. These particular lag screws are a half-inch-by-6-inch and a 3/8-inch-by-4-inch, both with hex heads (that is, external hex) and made from steel with a bright zinc coating (electroplated galvanization) for corrosion resistance. Dull gray coating with hot-dip galvanization is another common coating. The heads are cold-formed in a die, and the threads are rolled in another die. There is no machining (metalcutting) needed. See also File:Lag screws aka lag bolts 001.png.