Graphite Plugged SPHERICAL OILLESS BEARINGING is unit of two rings, outer ring and inner ring. The outer ring is made of 45# quenched steel with a hardness up to HRc40-43abd also the whole surface will be burnished.(In case under specific application, the inside surface of outer ring is plated hardened chrome.) The inner ring is made from a metal basis, Which may be all bronze or high strength brass, embedded with solid lubricant on its outside surface .