while other ball bearings adhere to ISO 492 or its regional equivalent (DIN, KS, etc.) There are five accepted levels of the ABEC/ISO 492 scale and the level is not related to the size of the bearing.

They incorprate a sealed bearing that is ... to the rolling action used by ball, roller, and needle bearings. Lubrication is crucial to the operation of plain bearings to avoid overheating due to ...