Backing your sandpaper with a cork sanding block allows you to reach a good middle-ground between the rigidity of a wood or plastic block, which helps to achieve a flatter surface, and the sensitivity of just using your fingers, which allows for following the acceptable undulations of a larger surface so as to finish the sanding more quickly.
Length : 100 mm (approx. 4") Width : 70 mm (approx. 2.75") Thickness : 25 mm (approx. 1")