• Used for quick and accurate setting of dial bore gages, Holtest and inside micrometers.
• If a setting ring of an optimal size is prepared, it can be used for calibration.

The Mitutoyo 177‑204 is a 4 mm steel setting ring used for accurate zero-setting and calibration of Mitutoyo inside micrometers, Holtest three‑point bore gages, and dial bore gages. This precision artifact provides a stable, certified internal diameter reference, ensuring high‑accuracy internal measurements in inspection, machining, and metrology applications.