At a glance
2RS
Usually an elastomer seal on each side. Contact, light-contact and non-contact versions need to be distinguished.
Start here when grease retention and exclusion of dust or splash are more important than minimum running drag.
ZZ / 2Z
Usually a pressed-metal shield on each side, separated from the rotating ring by a small gap.
Start here for a relatively clean enclosure where low closure drag and speed capability are priorities.
Key differences
Typical design distinctions. The complete designation and current product specification take precedence.
Swipe the table horizontally to see both options →
| What to compare | 2RS | ZZ / 2Z |
|---|---|---|
| Closure | Usually two elastomer seals | Usually two non-contact metal shields |
| Contamination | Contact designs generally offer stronger exclusion | Gap blocks larger particles; limited liquid exclusion |
| Friction | Contact lips add torque and heat | Normally little closure friction |
| Speed | Check the sealed version's limiting speed | Often higher than a contacting-seal version |
| Lubrication | Frequently supplied with retained grease | Frequently pregreased; shield is not a liquid seal |
| Substitution | Check seal material, torque, grease and clearance | Check whether the surrounding housing provides sufficient protection |
Before you choose
- A 608-2RS and a 608-ZZ may share 8×22×7 mm boundary dimensions while differing in grease, speed and sealing.
- A two-seal marking does not establish waterproof or washdown suitability.
- ZZ and 2Z are common conventions, not a universal code across every bearing brand.
Check the actual model
Search a full designation, inspect its technical data, then compare candidate records. Similar names or dimensions do not guarantee interchangeability.
Open the closure selector and full seal-code library →
Filters show recorded catalogue attributes. Open each candidate to confirm its exact specification.
A few things worth clarifying
Does 2RS mean better quality?
No. It describes a closure arrangement, not a quality grade or accuracy class.
Can I swap 2RS for ZZ?
Only after checking dimensions, allowable speed, seal drag and contamination conditions for the exact variants.
Reference basis & limits
- SKF Evolution — New sealing solutions for deep groove ball bearings
- NSK — Single-row deep groove ball bearings: features and closure designations
Independent explanatory content; not a manufacturer endorsement or approval of a replacement. Verify current product data, fits, lubrication and operating conditions before applying a comparison.