The thumb support enhances the ergonomics of the Leica M10 and M11 by slotting into the hot shoe. With the thumb pressed up against the thumb rest, the camera can be held much more steadily and is easier to handle. It makes shooting with one hand much steadier and allows the use of longer shutter speeds with less risk of camera shake. The thumb support is machined from brass and is finished in the same classic surface coating as the Leica M10 and M11 to ensure a perfect match when attached.