M_dyn interior to each of the five rings from the ^3DBAROLO fit to the H I velocity field (red open circles) of J0204–1009 and M_dyn derived from the W₂₀ value of its integrated spectrum and H I disc diameter (black square). Also shown are NFW model cumulative masses for two sets of NFW DM haloes, one set for an NFW concentration index of 3.0 (left panel) and the other for an index of 2.5 (right panel).