Backing up broad panels: It provides a solid, wide curved surface to support large sheet metal areas (like door skins, hoods, or roof panels) when tapping out low or high spots.
Matching gentle crowns: Its broad, mild radius prevents the accidental flat spotting or over-stretching of metal that can happen when using a flat or overly sharp dolly.
Metal finishing: Technicians use it in "hammer-off" or "hammer-on" techniques to help level out waves and return the panel to its original factory contour before priming and painting.