Hex bolts are a very common choice when it comes to construction and repair. Hexagon screw head bolts come in a large variety of sizes and diameters. The best way to choose the right hex bolt is to find the bolt material that best suits your needs. Each different hex bolt material has particular properties to fit specific applications. Hexagon screw head bolts are made from a variety of materials to accommodate the wide range of applications in which hex cap bolts are used.