These Holtests are versatile, self-centering three-point internal micrometers for the accurate and efficient direct-measurement of internal diameters. Three anvils, evenly spaced at 120° apart, contact the internal wall surfaces and find true alignment with the axis of the bore for accurate ID measurement.

• TiN-coated measuring contact points(over 6mm/.275" range models) provide excellent durability and impact resistance and allow the instrument to measure right to the bottom of a blind hole.
• Highly durable because of carbide-tipped contact points (anvils).
• Measurement can be taken closer to the bottom of the blind bore.
• Can measure deep holes using an Extension rod (optional) which is available on models over 6mm (.275") measuring range.
• With Ratchet Stop for constant force.
• Setting Rings for zero point adjustment are optional.
• Supplied in fitted plastic case up to 100mm / 4”. Over 100mm / 4” supplied in wooden case.

Technical Data

Graduation: 0.001mm, 0.005mm*,
.0001" or .0002"* (*over 12mm or .5” models)

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Optional Accessories
952322: Extension rod 100mm / 3.94” For range 6-12mm / .275-.5” models
952621: Extension rod 150mm / 5.9” For range 12-20mm / .5" - .8” models
952622: Extension rod 150mm / 5.9” For range 20-50mm / .8" - 2” models
952623: Extension rod 150mm / 5.9” For range 50-300mm / 2"-12” models

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Parts Break Down