Grade 2. Made of fully seasonal alloy tool steel with a Rockwell hardness of 65, providing both long wear and resistance to stains and rust. These blocks are manufactured under carefully controlled conditions, allowing for the highest degree of accuracy when used at temperatures of 68 degrees F (20 degrees C).

Sets are calibrated to meet or exceed federal specifications GGG-G-15a. One-year guarantee against factory defects. Complete certificate of calibration traceable to the National Institute of Standards & Technology (NIST) comes with each set. Includes fitted case.

Set contains:

• Nine blocks, .1001 to .1009, in .0001 steps
• 49 blocks, .101 to .149, in .001 steps
• 19 blocks, .050 to .950, in .05 steps
• Four blocks, 1 to 4, in 1-inch steps

Tolerances (in millionths) are as follows, .0001 step blocks, +4/-2; .001 step blocks, +8/-4; .05 step blocks, +10/-5; and 1-inch step blocks, +12/-6.