Starrett SA 711. - Square Steel Gage Block Accessory - Internal Measuring Machine Jaws (12mm)
The Starrett Internal Measuring Machine Jaws are double-ended, self-proving, assuring parallelism and squareness. Designed for use with square-style gage blocks, the jaws are made of hardened steel material, 50.8mm long, 25.4mm wide, and 12mm thick. Both side edges are lapped 90-degree square to the gaging faces within 30 seconds of arc and extend beyond the gage blocks in the combination, thus forming a square master.
See Data Sheet for additional details.