24: pulley: more used for mechanical transmission, the band and round by the friction between the transfer movement and torque, make the normal operation of mechanical energy. This factory production pulley beautiful shape, mechanical line feels strong, material and dense, molecular density distribution even, stable performance, size is exact, tensile and compressive strength good, smooth transmission, wheel tank and the maze &sealed ring in the hole and balanced, the small deviation, in the hole and shaft with accurate, can reach 0.01 mm, suitable for high speed use.