High Quality graded hardened chrome steel roller made from Chromium AISI 52100 steel. Hardened to 60-67 Rockwell Scale equivalent to 700-900 HV (Vickers Scale) and are hardened all the way through the roller. These are the same hardened steel rollers used to manufacture needle roller bearing assemblies and have a high duty and life cycle. These hardened rollers are highly suited as replacements for bearing components, drive transmission parts, pivots, shafts etc.