Grade 316 Stainless Steel Ball bearings made from AISI 316 Stainless Steel with a hardness of 25 - 39 Rockwell Scale. These are the same stainless 316 steel balls used to manufacture bearing assemblies and have a high duty and life cycle. Hardened stainless steel with good corrosion resistance to sea water, dilute nitric, sulphuric and acetic acids, photo chemicals, inks, bleaches, dyes etc. Can be machined / drilled.