Kirjes Inflatable Sanders are pumped up through an air inlet in the drive shaft located in the bottom of each sander.  The air valve design leaves the bottom flat without a clumsy protruding valve on the sanders. This patented solution made it possible to make superior cylindrical drum sanders as well as a unique rounded sander with a dome shape at the working end.  This molded rubber bulb constantly flexes and changes shape, making the sanders soft all the way to the edge.  With the choice of four grits from course to extra fine, Kirjes eliminates scratches and allows you to apply the sander’s total width against the work piece or to use only the edge in all kinds of complex sanding.  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 half sphere sander, needs to be pumped slightly harder than the drum sander to hold the sandpaper).