The compression device shall be equipped with an integral, yet removable, micrometer to gauge the percentage of compression by calculation: using the original thickness measurement (refer to 13.1), multiply by 0.75, 0.85, or 0.90 (refer to 17.5) the desired compression based upon the IRHD S2 hardness of the material, and apply the compressive force by tightening the nut until the micrometer displays the desired value