Idler Rollers or sometimes simply known as Conveyor Rollers are cylindrical-shaped bars that run along & underneath a conveyor belt. They also assist in the smooth, continuous movement of the material along the belt. Idler Rollers can be self-aligning & assist in maintaining the belt tracking. V-belt Pulleys are devices which transmit power between axles by use of a v-belt, a mechanical linkage with a trapezoidal cross- section.