36 pcs: 9 blocks .1001″ thru .1009″ step of .0001″, 9 blocks .101″ thru .109″ step of .001″, 9 blocks .110″ thru .190″ step of .01, 5 blocks .100″ thru .500″ step of .1″, 3 blocks 1″, 2″, 4″, 1 block .050″. Manufactured to meet N.I.S.T. Federal Specification ASME B89. 1.9 – 2002 tolerances on length for inch gage blocks. Certificate of Calibration traceable to N.I.S.T. In high-quality fitted wood case. Tolerances to ±.00005″.