Surface densities and exponential fits (straight lines): HI+He (blue exes); stellar disc (red pluses); implied disc DM (black diamonds); R^-1 power-law fits to the HI and projected URC profiles (green curves); optical radii R₂₅ (red arrows); radial and surface density range for HI exponential scale lengths h_HI (horizontal and vertial light gray dotted lines). Lower right: comparison of disc size with various scalelengths: HI+He (blue exes), stellar disc (red pluses), inner HI cutoff radii (green asterixes).