Type: The metal shaft is lighter in weight and has less fatigue for operator. The rubber shafts are more durable than metal but heavier in weight. Length: The shaft length is provided in various sizes to suit the individual geometry of the product. You have to select the adequate length of the shaft so that you can use the grinder comfortably with minimum bends and curves. At the same time avoid excess length of shaft, as the more the shaft length the more the cost and more the wear.