This specification was issued to cover peening balls suitable for an enhanced peening technique. The complete requirements for procuring the product shall consist of this document and the latest Issue of the basic specification, AMS2431. Peening balls conforming to this specification are typically intended for use in ultrasonically activated shot peening of metal surfaces to impart compressive stresses to these surfaces thereby increasing resistance to fatigue and stress corrosion cracking. These balls can also be used in the peen forming process.