My Spartan's came in these plastic cases. The 52' is black and the 55' is green. They were called Spartan due to lack of embellishments and creature comforts. There is a thumbscrew or wingnut on the underside for removal of the base. I do not know what the original brochures would show, but the 52' has a light and the 55' does not. I understand that they were the ultimate no frills Singers.
Rodney
Ponchatoula,la.