This standard is no longer an American National Standard or an ASME-approved standard. It is available for historical references only.

This standard contains complete general and dimensional requirements for Metric Series Hexagon Socket Flat Countersunk Head Cap Screws of nominal sizes from 3 mm to 20 mm recognized. 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 noted below.

This product is designed and recommended for applications where a flush seating socket head screw is desired. Wrenchability is limited by the socket size and key engagement. Becuase of the head configuration, this product is not recommended where maximum fatigue resistance is required.