... C2,C3,C4 4.widely usedsingle row cylindrical roller bearings, caged ,mainly of the NU,NJ ... NUP and N designs double row cylindrical roller bearings ,caged,mainly of the NNU and NN ... designs multi-row cylindrical roller bearings, caged single row full complement cylindrical roller bearings ,mainly of the NCF ... NNF design multi-row full complement cylindrical roller bearings, with four or eight rows of ...