Special Step Block for thickness and linearity calibration. This versatile block contains eight (8) steps. Set it down on one side and get the 1.0, 2.0, 3.0 and 4.0" steps. Then "TIP" it over and get the 1.5, 2.5, 3.5, and 4.5" steps. Step faces measures 1.00" x 1.00". Manufactured in accordance with PH Tool drawing no. 10068. Step thickness tolerance is ±0.002".