This Ball Bearing V-Block Set is ideal for use where inspection set-ups are not possible using plain V-Blocks. This unique product allows you to inspect and detect out of round conditions, defects, and lobes without damage to parts or blocks. Features include... Accuracy of ball sphericity: 0.000025" Balls finished to .2 micro inches, hardened to 62 RC Overall accuracy of matched pairs: + 5 microns Case iron base and housing are heat stabilized and seasoned Sold in pairs with clamps and test ball. Base Dimensions include... 2 3/16" square x 1 1/16" O/A Ht. Capacity Range: 3/64" -2.5" Ball Diameter: 0.5" diameter Wt. Capacity: 220lbs