How are the double seal bearings and other pattern bearings on the specifications and models?

How are the double seal bearings and other pattern bearings on the specifications and models?

Bearing type codeImports of bearings commonly used type code (refers to the beginning of the model numbers or letters, such as 6200, 6 is the beginning of deep groove ball bearings, NU, NJ for cylindrical roller bearings):Self-aligning ball bearing - 1;

Angular contact ball bearings - 7;Cylindrical roller bearings - N;Needle roller bearing - NA;

Spherical roller bearings - 2;Tapered roller bearings - 3;Thrust ball bearing - 5Deep groove ball bearings - 6;