Made from Grade 5 steel, these screws are suitable for fastening most machinery and equipment. Dimensions meet ASME B18.2.1 specifications. Grade 5 steel hex head screws are marked with three radial lines. Length is measured from under the head. Zinc-plated steel screws resist corrosion in wet environments. Match the thread spacing of mating components. Coarse threads are the industry standard; choose these screws if you don't know the threads per inch. Screws that meet ASTM A449 or SAE J429 comply with specifications and testing requirements for material quality.