9 Blocks from .1001" to 1.009". 49 Blocks from .101" to .149". 19 Blocks from .050" to .950". 4 Blocks from 1.000" to 4.000". Grades and Tolerances (Length) [Maximum permissible errors. Units = 1 millionth of an inch] Size of Gauge Up to and including 1" +4 -2, 2" +8 -4, 3" +10 -5, 4" +12 -6