Z vs. ZZ Shielded Bearings

A “Z” bearing and a “ZZ” bearing are both types of shielded ball bearings. The difference between them is that a Z bearing has a single metal shield on one side of the bearing, while a ZZ bearing has metal shields on both sides of the bearing.

The metal shields on a ZZ bearing provide greater protection against contamination and moisture than a Z bearing, which makes ZZ bearings suitable for more demanding applications.

Other letters besides RS and 2RS are used to denote different types of seals and shields in ball bearings. For example:

• R: A single rubber seal on one side of the bearing

• 2RZ: Two non-contact seals on both sides of the bearing

• 2Z: Two metal shields on both sides of the bearing

Different manufacturers may use different letter combinations to denote seals and shields, so it's important to consult the bearing manufacturer's specifications to understand the exact type of seal or shield used in a particular bearing.