What are the MIN and MAX readouts telling me about the surface of my part? The MIN and MAX readouts from your indicator are telling you the lowest and the highest point on the surface of your part, respectively. These measurements are determined by running the indicator across the surface of your part while rotating it along a centralized axis. The indicator will pick up on the points that are lowest and highest, allowing you to have a quantitative measurement of any discrepancies along the surface. These measurements are important for determining the flatness, roundness, concentricity, or any other intended shape. Once a part is made, testing the MIN and MAX of the surface is crucial to understanding if the part is shaped precisely the way it is supposed to be.