This section is mainly devoted to the description of the tests of the GRBM carried out by the BeppoSAX/GRBM hardware team on August 1995 at the ESA Technology Center (ESTEC) in Noordwijk, with the satellite almost fully (except solar panels) integrated. The goal of these calibrations was to define the shielding effect of the satellite materials in front of the lateral shields field of view (Fig. 1.3).