No wonder Axis Bearings are smooth. Got this from their parent companies website, Baart Industrial Group.
Deep Groove Ball Bearings
Axis manufactures bearings to incredibly close tolerances. Instead of the usual ABEC 1, Axis manufactures every bearing to meet or exceed ABEC 3 tolerances. Every Axis bearing uses grade 10 balls (normally only found in ABEC 5 or better), instead of grade 25. Grade 10 balls are rounder, more precise and share the load more evenly. All Axis deep groove ball bearings are noise and vibration tested. Polyrex EM grease, the lubricant of choice for the electric motor industry, is used in all Axis pre-greased bearings. In addition, Axis bearings feature high-strength, temperature-resistant steel retainers. All of these high-quality features add up to longer life.
Angular Contact Ball Bearings
All Axis angular contact ball bearings meet or exceed ABEC 5 tolerances. They feature forged rings for superior grain structure. The machined bronze retainer provides superior strength and heat dissipation. They come with a 40-degree contact angle for high thrust load capacity. All Axis angular contact ball bearings are universally flush ground allowing them to be paired in any configuration your application demands.