Reading a model number — series, bore code, seal suffix
2026-10-31
Taking the 100 real model numbers in our catalogue apart into three segments, including the four slash models and the single case where the bore rule does not hold.
A designation like 6205-2RS looks like a code, but it is three segments: series + bore code + seal suffix. This page tests those three segments against the 100 real model numbers in our catalogue — including the one that fails the rule.
Three segments
First segment: series
The first two or three characters are the dimension series, which fixes how large the outer diameter and width are for a given bore. Our catalogue carries six series:
| Series | Models | Bore range |
|---|---|---|
| 60 | 19 | 5–60 mm |
| 62 | 21 | 5–60 mm |
| 63 | 18 | 5–60 mm |
| 68 | 16 | 5–50 mm |
| 69 | 16 | 5–50 mm |
| 160 | 10 | 12–50 mm |
At the same 25 mm bore: 6005 is 47 mm outside, 6205 is 52 mm, 6305 is 62 mm. A larger series number means a larger outer diameter at the same bore, and therefore more capacity (see load ratings).
Middle segment: bore code
The last two digits map to the bore, following the usual industry convention:
| Code | Bore |
|---|---|
| 00 | 10 mm |
| 01 | 12 mm |
| 02 | 15 mm |
| 03 | 17 mm |
| 04 and above | code × 5 mm |
There is also a class of miniature models with a single digit: 605, 685 and similar, where the last digit is the bore in millimetres directly (605 → 5 mm, not 25 mm). This is the easiest one to misread.
Last segment: seal suffix
The suffix states the seal form. Our catalogue carries seven: Open, Z, ZZ, RZ, 2RZ, RS, 2RS. Every one of the 100 base models has all seven, making 700 specifications.
For what each suffix means and how they differ, see bearing suffix codes.
How our table actually writes them
Open is written as open
In the parameter table, open-type models are written 605open, 6205open — lowercase open, not blank and not O.
If you receive a model number with no suffix, confirm whether it means open type or whether the other party simply left it out.
Slash models: /22 and /42 are not the same thing
Four models in the catalogue carry a slash, and what follows the slash is not always the same quantity:
| Model | Bore d | Outer D | What the slashed number is |
|---|---|---|---|
| 60/22 | 22 | 44 | the bore (non-standard bore in the 60 series) |
| 62/28 | 28 | 58 | the bore |
| 62/32 | 32 | 65 | the bore |
| 6203/42 | 17 | 42 | the outer diameter (standard 6203 bore, non-standard OD) |
The first three carry the bore after the slash; the last carries the outer diameter. Do not guess on a slash model — check it against the table.
Tested against 100 models
The bore rule holds 99 times out of 100
Applying the bore rule above to all 100 model numbers:
| Type | Models | Rule |
|---|---|---|
| Miniature (single digit) | 25 | last digit = bore in mm |
| Code 00 | 5 | 10 mm |
| Codes 01–03 | 18 | 12 / 15 / 17 mm |
| Codes ≥ 04 | 48 | code × 5 |
| Slash | 4 | judged individually (above) |
99 match, 1 does not: 6203/42. Its slashed number is the outer diameter, not the bore. That exception is not a data error — it is a different naming convention. The rule is usable, but the exception exists.
A larger series number does not mean a larger bore
The bore ranges of the series overlap almost completely (60, 62 and 63 all cover 5–60 mm). The series decides thickness at a given bore, not the bore itself. For a 25 mm bore, series 60, 62 and 63 all offer one; which to take depends on load and space, not on "pick the smaller number".
What a model number does not tell you
This is not "our naming standard"
The three-segment structure above is the conventional industry meaning of the code, not a rule our company invented, and it constitutes no standard claim.
We stand behind exactly one thing: the actual spelling of these 100 model numbers in our parameter table, and their actual dimensions. Every number in the tables above comes from that table.
No tolerance, clearance or precision in the name
6205-2RS states series, bore and seal only. It does not carry:
- precision grade (all P0 in this table — see precision and clearance)
- radial clearance group (all C0 in this table)
- fit tolerances or material grade differences
- special requirements (high temperature, low noise, non-standard clearance and so on)
If your drawing specifies any of these, the model number alone is not enough — include them when you contact us (contact us).
Concrete cases for the miniature rule and the slash exception: 605 (last digit is the 5 mm bore) and 6203/42 (the slashed number is the 42 mm outer diameter).