The ball bearings in my cheap Chinese linear bearings on my 3D printer turned out to be steel (not stainless steel) and dull looking. The bearings didn't run very smoothly so I bought a replacement and now they work great! Their quality is much better than what was originally in my warehouses.
Bearing 608- ZZ1MC3E (8x22x7) NSK//80018
4 Review
π§ High-Quality TIMKEN 6203 2RSC3 6203 2RS Bearing - Size: 17X40X12mm
4 Review
Enhanced Performance Sydien SCS12UU Bearing Bushing Diameter for Precision Machinery
4 Review
π Wheels Manufacturing Ball Retainer Bag: Convenient Storage and Protection for Your Ball Retainers
6 Review