A 4.2-m-long Hall-probe bench was developed for high-precision magnetic characterization of insertion devices at the Brazilian Synchrotron Light Laboratory. In this paper, its mechanical and electrical features are described, as well as the procedures applied to improve accuracy and repeatability. Tests used to establish measuring precision were performed in a 2-T planar wiggler, which is 2.8-m long, with periods of 180 mm. The obtained fields were integrated and compared with the rotating-coil measurements.56627252730