164-325 Fullmetal Reduction Set (long countershaft) for use with 162-320 power drive unit. Supplied with various gears & belts to enable the user to achieve the following variations to increase the speed or torque: 1:1 Power & speed remain the same but the stability and accuracy is improved by the long countershaft. 1:2.77 The speed is increased. 2.77:1 The torque (power) is increased. Product is for Unimat Metaline Set - also compatible with Unimat Classic.