The ratchet exists so that two people get the same reading · review
The only micrometer the American relevé returned, and the only instrument on this shelf that measures a bore rather than a part.
What the figures leave us with The only genuine micrometer the American relevé returned, and a serious instrument: fifty to three hundred millimeters from one head, insulated rods marked with their own lengths so the set checks itself, and radius-ground anvils that sit properly in a bore. For measuring bores this is the tool and a caliper is not. What five hundred and twenty dollars does not buy is a published accuracy — only a 0.01 mm graduation and a claim to exceed standards that are never named.
NO accuracy figure. NO standard named. No thimble type.
Which is the opposite job from everything the shelf’s introduction describes.
An outside micrometer closes onto a part in a 25 mm (0.98 in) band. An inside micrometer is assembled to slightly less than a bore and wound open until it just touches.
A cylinder liner. A bearing housing. A ring gauge. The gap between two machined faces.
That is why none of the shelf’s ranges — 0–25, 25–50, 50–75 — appears here. An inside micrometer starts where a bore can physically admit it, and this one starts at 50 mm (1.97 in).
Which is the set argument, made as strongly as it can be.
This shelf’s introduction: the first decision is which range you need, and whether a set is better value than one tool.
A head, a series of rods and spacing collars cover a 250 mm (9.84 in) span. No single-range instrument covers it at any price.
And this page gives only the first.
Nought point nought one millimeter is what the scale can be READ to.
An accuracy figure is how far the reading can be from the truth — and on a 300 mm (11.8 in) instrument assembled from a head, a rod and collars, three components’ errors add up.
Starrett says its tools exceed national and international standards and names none of them.
The firm’s reputation is the implicit answer. It is not a number, and the introduction above says the number is the reason to own a micrometer at all.
Which is the detail that shows who made it.
Steel expands about eleven microns per meter per degree. A 300 mm (11.8 in) rod warmed two degrees by a palm is roughly seven microns longer.
That is most of a 0.01 mm graduation — reading high before the tool has touched anything.
Insulating the rod keeps the hand off the measuring length.
Which answers this shelf’s buying tip without a separate gauge.
“A micrometer sold with a setting standard is worth more than one without. The standard is how you confirm the tool still reads zero.”
Each rod is marked with its length. The instrument is checked against its own components.
On sale at around 520 € on the American Amazon store at the time of checking.
Prices and availability are what Keepa reported on the date this page was updated; both move.
Prices quoted in this text were read on 8 October 2026. The live price is at the top of the page.
| Measuring mode | An INSIDE micrometer: the head, rods and spacing collars are assembled to the required range and then adjusted until the instrument just spans the bore. That is the opposite job from the outside micrometer this shelf's introduction describes, and it is why none of the shelf's ranges — 0–25, 25–50, 50–75 mm (1.97 to 2.95 in) — appears here: an inside micrometer starts where a bore can physically admit it |
|---|---|
| Stated dimension or range | 50 mm (1.97 in) to 300 mm (11.8 in), assembled from a micrometer head, rods and spacing collars, in a 10-piece set. This shelf's introduction says the first decision is which range you need and whether a set is better value than one tool; a 250 mm (9.84 in) span from one head is the strongest possible answer to that, because no single-range instrument covers it |
| Resolution | Graduated at 0.01 mm intervals, stated. That is the GRADUATION — what the scale can be read to — and not an accuracy: a 0.01 mm graduation on a 300 mm (11.8 in) instrument says what you can see, not how close it is to true |
| Stated accuracy | NOT PUBLISHED. Starrett states that its precision measuring tools "exceed accuracy and performance requirements of national and international standards" and names NO standard and NO figure. This shelf's introduction says stated accuracy is typically an order of magnitude finer than a caliper's and that this is the reason to own a micrometer at all — on a five-hundred-dollar instrument, that figure is the one thing a buyer cannot check |
| Probe and body | Adjustable INSULATED rods, each MARKED WITH ITS LENGTH, and hardened, radius-ground anvils. Both details are functional rather than decorative: insulation keeps a warm hand out of a 300 mm (11.8 in) steel rod, where a tenth of a degree is microns of expansion, and a radius-ground anvil contacts a curved bore at a single point rather than rocking on an edge |
| Supplied | A ten-piece set in a protective vinyl-and-steel case. This shelf's buying tip says a micrometer sold with a setting standard is worth more than one without — and on this set the RODS are the standard: each is marked with its length, so the instrument is checked against its own components rather than against a separate gauge block |
| Also stated | Starrett has made dimensional measuring tools since 1880. No thimble type is published — and an inside micrometer has no ratchet or friction thimble in the sense this shelf's introduction describes, because the operator feels the fit in the bore rather than closing onto a part |
| Amazon reference | B000KU80WK |
| EAN | 0049659561425 |
Bores, rings and parallel internal faces — the dimension an outside micrometer cannot reach. A cylinder liner, a bearing housing, a ring gauge, the gap between two machined faces: all of those are measured from the inside out, by assembling an instrument to slightly less than the dimension and winding it open until it just touches. This shelf's introduction describes outside micrometers in 25 mm bands; this is the other half of the family, and a workshop that measures bores needs it whatever outside micrometers it owns.
That is the question to put to the seller, because they are not the same thing and this shelf's introduction asks for the second. A 0.01 mm graduation says the scale can be read to a hundredth of a millimeter. An accuracy figure says how far the reading can be from the truth — and on a 300 mm (11.8 in) instrument assembled from a head, a rod and collars, the errors of three components add up. Starrett says only that its tools exceed national and international standards without naming one. The firm's reputation is the implicit answer, and it is not a number.
Because steel grows in your hand and at 300 mm (11.8 in) it grows measurably. Steel expands about 11 microns per meter per degree, so a 300 mm (11.8 in) rod warmed by two degrees from a palm is roughly 7 microns longer — which is most of a 0.01 mm graduation, and it is reading high before the tool has touched anything. Insulating the rod keeps the hand off the measuring length. It is the kind of detail that only appears on instruments made by people who have watched somebody chase a drifting reading, and no other product in this relevé has anything like it.
Details checked on October 8, 2026.
Bores, rings and parallel internal faces from 50 to 300 mm (1.97 to 11.8 in), in a shop that already owns outside micrometers
Specifications: the manufacturer sheet for measuring instruments and the matching Amazon product page. Prices and availability: Keepa. Every figure on this page names its source.
0–25 mm (0 to 0.98 in) · 0.001 mm resolution · ± 0.003 mm accuracy · carbide tip
The only micrometer in this hub that publishes resolution and accuracy as separate figures — 0.001 mm and ± 0.003 mm — on a carbide measuring tip.
Best for: Anyone who wants to know what the instrument actually guarantees before buying it.
0–25 mm (0 to 0.98 in) · 0.001 mm resolution · hardened alloy head · CR2032
A digital micrometer over 0–25 mm (0 to 0.98 in) with a 0.001 mm display step and a hardened alloy measuring head, running on a CR2032 cell.
Best for: Somebody who wants micrometer resolution without learning to read a thimble.
0–25 mm (0 to 0.98 in) · 0.01 mm resolution · carbide faces · spindle lock
A mechanical micrometer over 0–25 mm (0 to 0.98 in) reading to 0.01 mm, with carbide measuring faces and a spindle lock, at a quarter of the price of the digital ones here.
Best for: Learning to use a micrometer, and for a workshop that wants one that never has a flat battery.
