The layout of a manual is roughly the same as a piano keyboard, with long, usually ivory or light-colored keys for the natural notes of the Western musical scale, and shorter, usually ebony or dark-colored keys for the five sharps and flats. A typical, full-size organ manual consists of five octaves, or 61 keys. Piano keyboards, by contrast, normally have 88 keys; some electric pianos and digital pianos have fewer keys, such as 61 or 73 keys. Some smaller electronic organs may have manuals of four octaves or less (25, 49, 44, or even 37 keys). Changes in registration through use of drawknobs, stop tabs, or other mechanisms to control organ stops allow such instruments to achieve an aggregate range well in excess of pianos and other keyboard instruments even with manuals of shorter pitch range and smaller size.