The "V" shape of the V-Belt tracks in a mating groove in a pulley or sheave, with the result that the belt cannot slip. V-Belts are also available with cogs, which further increase their efficiency. Many drive systems utilize multi-grooved sheaves to accommodate multiple V-Belts, depending on drive horse power and torque requirements. Such drives can utilize multiple individual V-Belts or the belts may have a common backing. V-Belts come in five width sizes, are standardized between manufacturers and are available in a number of different lengths.