Bearing suffix codes: what ZZ, 2RS, C3 and N mean
Two bearings can share the same bore and outside diameter and still be different parts. The suffix decides the seal, the internal clearance and whether the outer ring locates.
Seals and shields
These decide how the bearing keeps dirt out and grease in:
- ZZ — metal shields on both sides; lower friction, less sealing, common on electric motors.
- 2RS (or 2RSH) — rubber seals contacting the inner ring on both sides; better protection, higher drag.
- Z or RS alone — one side only; commonly used where the other side is protected by the housing.
- Open (no suffix) — no shield; needs external sealing and clean lubrication.
Internal clearance
Measured before mounting, clearance changes with fit and temperature:
- C2 — smaller than normal clearance.
- CN (usually omitted) — normal clearance.
- C3 — larger than normal; typical where the inner ring runs hot, e.g. motor drive ends.
- C4 — larger than C3; for heavy thermal expansion.
Other letters you will meet
Small letters change fit and function, and they are the easiest to lose when reading from a photo:
- N, NR — snap-ring groove, and groove plus ring, on the outer diameter.
- TN9, TVH — moulded or glass-fibre reinforced cage.
- P6, P5 — precision grades; higher grades are usually ordered, not stocked.
Read the whole string
A number like 6205-2RS-C3 is bore and series (6205), sealing (2RS) and clearance (C3). Give all of it, plus the application and operating temperature, and the supplier can confirm rather than guess.
Never substitute a suffix because the right variant is out of stock: a C3 bearing in a preloaded application, or an open bearing where a sealed one was specified, causes failures that are blamed on the part supplier.
Other guides
- How to read an industrial nameplate before asking for a price
- Four measurements before ordering a hydraulic hose
- Three checks on a pneumatic solenoid valve
- How to measure an O-ring or oil seal correctly
- How to describe a part you cannot identify
- Compatible, OEM or genuine: what the word on a quotation actually commits you to