ISO 148-3:2016 specifies the requirements, preparation and methods for qualifying test pieces used for the indirect verification of pendulum impact testing machines in accordance with ISO 148‑2. It specifies notched test pieces with nominal dimensions identical to those specified in ISO 148‑1; however, the tolerances are more stringent. NOTE 1 The chemical composition or heat treatment, or both, are varied according to the energy level desired. NOTE 2 Reference test pieces are qualified on reference pendulum impact testing machines which are also described in this part of ISO 148.