What Does 2RS Mean on a Bearing?
If you've ever ordered a bearing and seen suffixes like 2RS1, 2RSR, DDU, LLU, or 2Z, you've encountered bearing seal designations. Every major manufacturer uses different letters for the same thing, which causes endless confusion. This guide explains exactly what each suffix means and when to use which type.
The Three Sealing Options
Every bearing comes in three basic configurations: open, shielded, or sealed. The suffix (or lack of one) tells you which you have.
| Configuration | Suffix | Rolling Elements | Lubrication | Best For |
|---|---|---|---|---|
| Open | (none) | Exposed both sides | External (grease housing or oil bath) | Clean environments, high speed, accessible for relubrication |
| Shielded | 2Z / ZZ | Metal plates, small gap to inner ring | Pre-greased, partial protection | High-speed clean applications |
| Sealed | 2RS / 2RS1 / 2RSR / DDU / LLU | Rubber lips contacting inner ring | Pre-greased for life, full seal | Dirty/wet environments, maintenance-free |
Open bearings run cooler and faster than sealed bearings because there's no contact friction from a seal, but they need more maintenance and aren't suitable for dirty environments.
Shielded bearings have thin metal plates pressed into the outer ring on both sides. The shields don't touch the inner ring — there's a small gap. This keeps large particles out and grease in, but isn't fully sealed. The gap means fine dust and moisture can still enter over time.
Sealed bearings have rubber lips that contact the inner ring on both sides, creating a full seal. They're pre-greased for life and require no maintenance. The contact friction means slightly lower speed limits than shielded bearings, but they're the right choice for most applications where contamination is a concern.
Why Every Brand Uses Different Letters
This is the part that trips everyone up. SKF, FAG, NSK, NTN, and Timken all make physically identical bearings but give them completely different suffix codes.
Double rubber seal (most common)
| Manufacturer | Suffix | Example |
|---|---|---|
| SKF | 2RS1 | 6205-2RS1 |
| FAG | 2RSR | 6205-2RSR |
| NSK | DDU | 6205DDU |
| NTN | LLU | 6205LLU |
| Timken | 2RS | 6205-2RS |
All five are the same bearing with the same rubber seal. The suffix difference is purely a naming convention — the physical bearing is identical.
Other seal types
| Seal Type | Common Suffixes | Notes |
|---|---|---|
| Double metal shield | 2Z, ZZ | Most brands converge here — one of the rare consistent naming conventions |
| Single rubber seal | RS | One side sealed, one side open |
| Single metal shield | Z | One side shielded, one side open |
Single-side configurations are less common and used in specific applications where one side needs to be open for lubrication access.
2RS vs 2Z — Which Should You Use?
| Factor | 2RS (Sealed) | 2Z (Shielded) |
|---|---|---|
| Contamination protection | Better — full contact seal | Partial — small gap allows fine dust/moisture |
| Friction | Higher | Lower |
| Maximum speed | ~80% of open bearing | Higher than 2RS |
| Temperature tolerance | Lower (rubber degrades) | Higher (metal doesn't degrade) |
| Maintenance | None — sealed for life | None — pre-greased |
| Best environment | Wet, dirty, outdoor | Clean, dry, high-speed |
The practical rule:
If your bearing is exposed to water, dirt, or outdoor conditions, choose 2RS. If it runs at high speed in a clean, dry environment, 2Z is often the better choice. When in doubt, 2RS is the safer default for most industrial applications.
The C3 Clearance Suffix
You'll frequently see bearings listed as "6205-2RS1 C3" — the C3 refers to internal clearance, not sealing.
C3 means slightly more internal clearance than standard, used when the bearing will run hot or be pressed into a tight housing. It's completely independent of the seal type. A bearing can be open, shielded, or sealed in any clearance class.
| Suffix Type | What It Describes |
|---|---|
| 2RS, 2Z, etc. | Sealing configuration |
| C2, C3, C4, C5 | Internal clearance class |
You can mix and match: 6205 (open, standard clearance), 6205-2RS1 (sealed, standard clearance), 6205-2RS1 C3 (sealed, increased clearance), and so on.
Don't Mix Seal Types When Replacing
When replacing a bearing, match the seal type exactly. If the original was sealed (2RS), replace it with a sealed bearing. Swapping a sealed bearing for an open one in a dirty environment will cause premature failure.
The seal type was specified for a reason.
Look Up Any Bearing's Equivalent
If you have a bearing part number from one brand and need to find the equivalent from another — including confirming the seal type matches — search it on Partmatch. Paste any bearing number and get verified equivalents across SKF, FAG, NSK, NTN, and Timken instantly.
Search any bearing part number →
For more on bearing nomenclature, see our guides on:
Partmatch provides verified bearing cross-references across SKF, FAG, NSK, NTN, Timken, and 30+ other manufacturers. Search any part number to find equivalents and pricing.