An edge sander does one job properly: sanding the narrow edge of a panel or door without rolling over and rounding it off. It sits on the full width of the edge and stays square from the first pass, on edges from about 5 to 60 mm and at angles from 43° to 92°. Two modes: a hard setting that holds the set angle for pre-sanding, and a soft setting that follows the surface for intermediate work. Against a hand block it roughly halves the time, and more to the point it removes the risk of sanding through a veneer or a paint edge — the failure that costs an afternoon rather than a minute.
Compare products and choose the right one for your work.