Some manufacturers list the “Mean Time Between Failure” for their products, but this is not a reliable indicator of expected life for LED Drivers. Thomas Research Products includes this metric, but also includes the “Design Life” of the product. A FIT Rate (Failures In Time) is a statistic for a component that measures how many failures the component will have per one billion operating hours. The lower the FIT Rate for a component, the better the component. FIT Rate is used to find Calculated MTBF.