This report describes the results of a supplementary comparison between SIM NMIs, which is being carried out in order to compare the degree of equivalence in volume measurements of stainless steel mass standards. For this comparison was selected a set of weights, with the following nominal values: 2 kg, 1 kg, 200 g and 1 g. KEY WORDS FOR SEARCH Density, volume, weights, 2 kg, 1 kg, 200 g, 1 g, supplementary comparison, SIM, CENAM, INACAL, INM, INEN, INTN and LACOMET. Main text To reach the main text of this paper, click on Final Report . Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/ . The final report has been peer-reviewed and approved for publication by the CCM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).