Ninja ABEC 5 Bearings. Each NiNjA ABEC bearing is tested at the final stage of the manufacturing process and is guaranteed to meet or exceed all ABEC standards (also JIS), including noise fall-outs. The ABEC rating on NiNjA shields is authentic, something most of our competitors have trouble being honorable with. All NiNjAs feature rings cut from high carbon bearing steel (SUJ2), a metal composition that for skating applications is superior to the SAE52100 found in most other brands. All NiNjA ABEC bearings feature AKS hardened balls, ground and polished to perfection in our facilities. Ball matching is implemented and the entire facility is a "clean room".