Description
Product Overview
Measuring small bores under 10mm to genuine micron accuracy is one of the tightest jobs in the toolroom — and a two-point bore gauge simply can’t self-centre reliably in that size range. The Mitutoyo 368-161 Holtest is built specifically for this work: three carbide-tipped anvils spaced at 120° that lock onto the true bore axis automatically, giving you a direct, repeatable reading with no operator “feel” required. In the 6-8mm range, this is the essential tool for fuel injector bores, small hydraulic components, precision bushing ID, pin gauges, and any tight-tolerance small-bore work where a vernier caliper would be laughed out of the QC department. This example is in like-new condition with its tools in the fitted case.
- True 3-point self-centring via three carbide-tipped anvils at 120° — automatically aligns to the bore axis, no rocking or wiggling required.
- 0.001mm graduation on the vernier scale for genuine micron-level direct reading.
- ±2μm accuracy — top of the class in this size range; a real inspection-grade tool.
- Carbide-tipped contact points (standard on sub-12mm Holtests) for extreme wear resistance in the fine small-bore sizes.
- Ratchet stop delivers consistent measuring force so readings don’t vary between operators.
- Ideal for injector bodies, fuel system components, small valve guides, precision bushings, hydraulic spools, and small pin/bore fit verification.
Condition
Used (Like New / Lightly Used).
This 368-161 presents in genuinely like-new condition. The carbide anvils are clean and unmarked, the ratchet stop operates smoothly with a crisp click, and the thimble turns evenly throughout its full range with no backlash or sticking. The satin chrome finish on the thimble and sleeve is clean with no visible handling marks. Supplied in its original fitted plastic Mitutoyo case with the correct accessory tools (wrench/spanner for anvil adjustment). No setting ring is included with this listing — a 6mm or 8mm setting ring is essential for zeroing the mic, so please check our current stock for a matching ring, or supply your own before use. As with any precision mic, we recommend zeroing against a calibrated reference before production measurement.
Included:
- 1 x Mitutoyo 368-161 Holtest 3-Point Internal Micrometer (6-8mm)
- Original fitted Mitutoyo plastic case
- Factory-supplied adjustment tools
Not included: Setting ring (check our stock listings for a matching 6mm or 8mm ring)
Brand Information
Mitutoyo is the global standard-bearer in precision metrology — founded in Tokyo in 1934 and the benchmark that every other manufacturer is measured against. The Holtest three-point internal micrometer line has effectively defined the category since its introduction; when an engineer specifies a “3-point bore mic” on a drawing, they almost invariably mean a Holtest. In the sub-12mm sizes, Mitutoyo uses carbide-tipped anvils rather than TiN coating, making these small-bore Holtests particularly durable for the intricate work they’re designed for.
Specifications
| Feature | Specification |
|---|---|
| Brand | Mitutoyo |
| Model | 368-161 |
| Type | 3-Point Internal Micrometer (Holtest) |
| Series | 368 Series Holtest |
| Measuring Range | 6 – 8 mm |
| Graduation | 0.001 mm |
| Accuracy | ±2 μm |
| Measuring Method | 3-point self-centring (anvils at 120°) |
| Contact Points | Carbide-tipped |
| Force Control | Ratchet stop |
| Country of Origin | Japan |
| Condition | Used — Like New |
| Included | Holtest mic, fitted case, adjustment tools |
| Not Included | Setting ring (check stock for matching ring) |
Keywords
Mitutoyo 368-161, Mitutoyo Holtest 6-8mm, Mitutoyo 3 point bore micrometer, small bore micrometer, Mitutoyo 368 series, 3 point hole micrometer, precision internal micrometer, Mitutoyo Holtest, self-centring bore micrometer, micron bore micrometer, Mitutoyo inside micrometer, Japanese bore micrometer
