Circumstellar medium radial-density distribution derived for SNe 2018jmt (blue) and 2019cj (red). The typical range found for a sample of SNe Ibn is shown by the grey-shaded area. For comparison, the CSM distribution by a steady-state mass loss is shown by the dashed lines for the CSM density parameter of A_* = 30 000 and 1000 (corresponding to D′ = 6 and 0.2 with s = 2.0). On the bottom, the look-back time in the mass-loss history is indicated, assuming v_w = 500 − 1000 km s⁻¹.