With the Mitutoyo 177-146 steel setting ring with a 50 mm nominal diameter, you quickly and accurately zero and calibrate your internal measuring equipment. Suitable for inside micrometers, three-point internal micrometers, and bore gauges, this reference standard prevents measurement errors and calibration drift in precision machining workshops and metrology laboratories. The high cylindrical accuracy and marked actual size ensure dependable measurements every time. Built from durable hardened steel with an 85 mm outside diameter and 20 mm thickness, it delivers lasting dimensional stability for demanding daily inspection tasks.