DESCRIPTION

• Mitutoyo Calibration Tester, Code No. 521-102, Series 521, made in Japan
• Bench instrument used to check and calibrate the measuring accuracy of dial indicators, dial test indicators, and other short-range comparison gauge heads against a precision micrometer-driven standard
• Universal holding bracket accepts a wide range of indicators and test-indicator lever heads
• Large knurled micrometer drum with dual color-indexed (red/black) vernier graduations for direct reading in both directions
• Carries an original brass U.S. government property tag stamped "U.S.A.T.C.A.A.P. 179373," reflecting prior institutional/military ownership — a nice provenance detail for collectors

SPECIFICATIONS

• Resolution: 1 division = .00001 inch (confirmed on drum)
• Measuring range: [confirm actual travel before posting — the 521-102 is a short-range inch model; verify and insert exact range]
• Clamping capacity (per Series 521): approx. .157"–.394" / ø4–10 mm
• Green hammertone cast body
• Serial number present on data plate — [read directly off the plate and insert; not fully legible in reference photos]

WHAT'S INCLUDED

• Calibration tester unit only
• No fitted case
• No indicators or accessories

CONDITION

• Used, complete, and cosmetically clean
• Mechanically free: the micrometer drum turns smoothly through its numbered travel, the vernier scale is intact, and the indicator-holding station with both knurled adjusters is present and moves
• Light surface rust on a couple of the knurled knobs; minor handling marks consistent with age
• Sold as-is, uncalibrated — measuring accuracy has not been certified or verified
• Original factory instruction labels present ("unscrew both bottom screws before use," etc.)