The bearing can be classified as double split-inner-ring (QJ series) and double split-out-ring (QJF series). The race track of the inner and outer ring is like an arch. When the inner and outer ring are impacted in the radial direction, theoretically, the steel ball contacts the inner and outer ring in four points. The inner and outer ring can be dissectible, so more steel balls can be loaded. The bearing can sustain axial load from double directions, the cage in use is solid brass cage.