Superior button head cap screws Zinc, also known as \”socket head cap screws,\” \”Allen bolts,\” or simply button head bolts. They are finished with a zinc plating to prevent corrosion.It can be used to fix steel to steel or timber to steel in construction with a matching hex nut, or it can be used for high strength bolting into threaded components and assemblies in manufacturing and engineering. Please consult the chart for precise measurements of the \”button\” size in our button head bolts.