Fowler 53-686-394-0 Master Ring 3.151-3.940"

Features:

• X Class
• Used for accurate setting of internal measuring instruments.
• Made from oil-hardened, non-shrinking gage steel, hardened and tempered to Rockwell 62C
• Subzero treated at minus 80°C for dimensional stability.
• Actual size etched on each master ring.
• Calibrated at 20°C in laboratory conditions.
• Furnished with a manufacturer's certificate of calibration.
• Metric rings available on special order.