Precision Boxed Metric Set of 1-2-4 Blocks (2pcs.)

1-2-4 Pair of Precision Ground Metric Blocks 25mm 50mm 100mm
Precision hardened & ground on all surfaces.
Extreme accuracy being flat to within 0.0001".
Parallel to 0.0003"
Hardened to HRC 56-60
Holes are threaded 3/8"
3/8-16" UNC thread