The sander actually becomes flat when pressed against a flat surface and round when pressed against a round surface i.e. the sanders conform to the underlying surface. Consequently the sanders should be filled with very little air. The #140 Drum has a 1 5/8" Diameter and is 1 5/8" long with a 1/4" Dia Shaft.
This is the most revolutionary sanding system to come out in years. Guinevere uses inflatable rubber sanders, each with four sanding sleeves. They can be fitted either to a flexible shaft or the quiet 1⁄2 HP motor. Watch our Video ...see below!