Variation in the radially dependent parameters of the final models. From top to bottom: the H i surface density, the rotation velocity, the inclination, the position angle, and the vertical scale height. Blue indicates the approaching side, red the receding side. For NGC 4217, the parameters of the B+R2 model for the outer ring are also shown. The dashed vertical line shows (approximately) where the main disk meets the outer ring. For NGC 973, the flare from the F model (Sect. 5) is shown as the dashed red line. The uncertainties are represented by the error bars.