... difference of rolling number. Single Row:N,NU,NJ,NF,NUP,NFP,NH. Double Row: NN,NNU , NNF Other:FC,FCD1 ... row cylindraical Roller Bearing can be classified in NU,NJ,NUP,N,NF and so on .Inner ring outer ring are ... 20mm-800mm.9.Variations of structure:NU,N,NJ,NF,NUP,NH,NCL...V,NB,NU...V,NNU,NNCF,NNCL,NNCS ...