There are many non standard bearings in deep groove ball bearings, with extended inner ring series is the most commonly used one. Standard 6201's dimension is 12x32x10 mm,with extended inner ring on both side,Hongtai's 6201-ZZ/B28 is customized,the dimension is 12x32x28,and mainly used for casters,wheels,furniture parts etc. The extended inner ring reduces the cost,more widely used. High quality bearing steel makes the lifespan longer,multitudinous dimensions of inner rings available.
