One-Two-Three Gage Block, Tolerance 0.0001 In Parallelism, 55-60 RC Hardness, 0.0001 In Squareness and 0.0001 In Flatness, Hardened Ground Steel, Grinding Step 1, 2, 3 In, Tapped Holes 5, Untapped Holes 18, Includes 2 Blocks, Hex Wrench, 5 Mounting Bolts, and Case

