The actual user of a ball bearing is going to be able to determine the lifespan of the bearing easier than a Houston bearing supply vendor. The calculated life of a bearing is commonly referred to as the L10 life. To calculate the L10 an assumption must be made, the assumption is the bearing will make “X” amount of revolutions before any type of metal fatigue occurs. Fatigue is making reference to the breakdown of metals or gradual weakening because of constant strain. Because the person using the bearing knows more about the environment that, the bearing is used and the type of stress placed on the bearing he will best be able to determine the L10 or at least provide an accurate estimated time frame.