Not all featherweights had the model number on them. Previous to about 1956 it was not included. My 1958 model has it while my 1950 featherweight does not. All black featherweights came in the black squarish suitcase type box with flip up hinges that lock. The white featherweights came in gray or turqoise heavy vinyl cases or two tone tan/green rectangular cases. Only featherweights and 301'a have flip up machine beds (to access the bobbin and store it in the case). The size of the machine, the case and the flip up bed are all sure fire ways to identify a featherweight. You may see them advertised as feather lites (no such thing) or old Singers in a suitcase.