Power transmission belts and belt pulleys are used to transmit power to different parts in a system. Power transmission belts come in a variety of types, such as V-belts and timing belts. V-belts have tapered cross-sections that lodge into the grooves of V-belt pulleys to transmit high torque and reduce slipping caused by under-tensioning. Timing belts are toothed belts used with toothed timing belt pulleys. They require less tension than other belt and pulley types due to their interlocking teeth.