This standard is no longer an American National Standard or an ASME-approved standard. It is available for historical reference only. This Standard contains the general and dimensional requirements for Metric Series Hexagon Socket Button Head Cap Screws of nominal sizes from 3 mm to 16 mm recognized as an American National Standard. Also included are appendices covering formulas for dimensions, part numbering system and preferred sizes for government use, and thread dimensions. The application of these screws is limited by their design as denoted below. This product is designed and recommended for applications where a lower head profile than that of the normal socket head cap screw (ASME/ANSI B18.3.1M) is required to prevent interference. Wrenchability is significantly reduced due to the smaller sockets and shallower key engagements and, because of the head configuration, the property class 12.9 tensile loads will not be met. It may be necessary to assemble this product using a nut to develop the full clamping capability. The inclusion of dimensional data in this Standard is not intended to imply that all of the products described are stock production sizes. Consumers are requested to consult with manufacturers concerning lists of stock production sizes.