Comparison : Item # N3-04020B4, Flat Faced Extra - Hard Polyurethane
Item # N3-04020B4-5R, Flat Faced Extra - Hard Polyurethane
Item # N3-04020B4-5R-C3, Flat Faced Extra - Hard Polyurethane
Item # N3-04020B4-5D, Flat Faced Extra - Hard Polyurethane
Item # N3-05020B4, Flat Faced Extra - Hard Polyurethane