This authentic OEM sourced replacement part is specially designed for use with Powermatic and Jet equipment. Ball bearings are generally utilized to reduce the friction between rotating parts. The balls or rollers take the load and spin, distributing the weight evenly while the minimal contact area of the ball reduces friction. Unfortunat...Read moreely, over time components will wear out and may begin to fail eventually requiring a replacement to maintain peak performance. Keep in mind this high-quality item is made of durable metal and is sold individually.