It has been developed to be having the performance of self-aligning,to be having the rotation of the inner rings,to be having the high speed and good reliability of bearing units with punch rings and punch or plastic pipe.For which,it had been in the place of being no aligning in performance,rotated in the outer ring ,cast iron pipe or inner ring was incorporated with the pipe to the units in lower speed.With lighter weight and lower cost,it has realized the parts systematization,Light weight good credibility and long life usage.