Lowest price:$249.99Description: Made from alloy tool steel with a Rockwell hardness of 65 to provide for long wear and resistance to stains and rust Each block meets or exceeds Federal specification GGG-G-15A Manufactured under carefully controlled conditions allowing for the highest degree of accuracy when used at a temperature of 68°F Grade 2 (A+) Accuracy +4 / -2 MILLIONTHS 81 Pc Set Includes 9 Blocks .1001” thru .1009” - Step .0001”, 49 Blocks .101” thru .149” - Step .001”, 19 Blocks .050” thru .950” - Step .050”, 4 Blocks 1.000” thru 4.000” - Step 1.000”