ABEC rated bearings have precision ground and polished raceways made from hardened chrome steel. Their internal tolerances are even greater than semi-precision bearings which make them capable of even higher speeds, higher load capacities, and longer life. The high internal tolerances and polished raceways make the bearings incredibly smooth and almost completely silent in operation.
Metal ABEC bearings have steel outer races that can be installed directly into roller tubes. They are heavily sealed bearings designed for heavy loads and dirty environments. Most feature rubber contact seals covered by metal shields to protect the bearing in the dirtiest environments. They offer all the benefits of poly-housed ABEC bearings but are more durable, better shielded, and do not require a crimp, which means they are replaceable. Round bore bearings in this category feature extended inner races and set-screws to help lock the bearing to the axle.
