Profiles of a selection of DIBs with various strengths and widths with respect to the heliocentric radial velocity. DIBs with similar and different profiles in M 1-20 (in black) relative to HR 6716 (in red) are displayed in the left and right panels, respectively. The profiles are shifted vertically for clarity. The Na I profiles at the bottom show the interstellar components (marked with black vertical lines) seen in M 1-20 and HR 6716. The DIBs displayed in the two panels are consistent with the higher reddening of E(BV) = 0.80 for M 1-20 as compared to E(B − V) = 0.22 for HR 6716. The stellar (and nebular) radial velocity range for M 1-20 is denoted by blue vertical lines.