1 roller and raceway contact or repair offline contacts, radial load capacity, suitable to withstand heavy load and shock load. [1] 2. Friction coefficient is small, suitable for high speed, speed limit near the deep groove ball bearings. 3. N type and NU type can move axially, to accommodate misalignment due to thermal expansion or of the shaft and the housing due to changes in relative position, can be used for supporting the free end. 4 pairs of shaft or housing bore machining higher, bearing outer ring axis relative deflection after installation should be strictly controlled to avoid contact stress concentration. 5 inner or outer ring detachable, easy installation and removal.