91-310-3 Ball Bearing V-Blocks Set - LargeThis 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. 00005" 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