Mitutoyo Surftest SJ-220 Features: 0.75 mN vs 4 mN — Which One Do You Need?
Choosing a Mitutoyo Surftest SJ-220 comes down to one question: will the stylus damage your surface? The SJ-220 is sold with two detector versions, 0.75 mN and 4 mN. This guide explains the difference so you can pick the right one for your parts.
Quick answer: If you measure soft, delicate or easily scratched surfaces (resin parts, thin coatings, finely polished metal), choose the 0.75 mN version (178-741-11). If you mainly measure hard machined metal parts, the 4 mN version (178-742-11) is the standard choice.
0.75 mN vs 4 mN at a glance
| 0.75 mN version | 4 mN version | |
|---|---|---|
| Mitutoyo code | 178-741-11 | 178-742-11 |
| Measuring force | 0.75 mN | 4 mN |
| Stylus tip radius | 2 µm | 5 µm |
| Stylus tip angle | 60° | 90° |
| Best for | Soft or delicate surfaces, fine finishes | General machined metal parts |
| Product page | View 0.75 mN version | View 4 mN version |
Why measuring force matters
Illustration of the two stylus tips (not to scale).
A surface roughness tester drags a diamond stylus across the part. A lower measuring force and a finer tip reduce the risk of leaving a mark or deforming the surface, which matters on plastic and resin components, soft coatings and finely lapped metal. On hard steel or cast iron parts, the 4 mN detector with a 5 µm tip is the common general-purpose setup.
What is the Mitutoyo Surftest SJ-220?
Mitutoyo Surftest SJ-220. Both versions share the same main unit; the difference is the detector.
The SJ-220 is Mitutoyo's portable surface roughness tester, built for checking parts on the shop floor instead of bringing them to a lab. Mitutoyo America announced it in March 2025 as a new model in the portable Surftest line. If you have been using or searching for the SJ-210, the SJ-220 is the newer model in the same portable line.
- 2.8-inch color touch screen
- Menus switchable between 25 languages
- Built-in battery, rated by Mitutoyo for approximately 1,000 measurements on a full charge
- Compatible with ISO 21920, as well as ISO 4287, ISO 13565, ISO 12085, VDA, JIS and ASME
- Wireless display of results and measurement settings with the optional U-WAVE-TIB
- Free SJ Communication Tool software for data handling
Drive unit options
Besides the standard drive unit covered in this guide, the SJ-220 family also includes a retractable drive unit type and a transverse tracing drive unit type for measuring in narrow places such as grooves. The two models we stock (178-741-11 and 178-742-11) use the standard drive unit.
Which one should you buy?
- Resin, plastic, coatings, mirror or lapped finishes: SJ-220 0.75 mN (178-741-11)
- Machined steel, cast iron and other hard metals: SJ-220 4 mN (178-742-11)
- Not sure? Send us the material and finish of your parts and we will help you choose.
We stock genuine Mitutoyo measuring instruments, including both Surftest SJ-220 versions. Orders ship from Japan with tracking, and US orders include import duties.
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