Late 1940s/ early 1950s if I remember. They came out after the war I know that much. Not entirely rare as they ran for a good many years. Never seen that one with that model of belt cover cap. I have one that has the rare upright conversion setup, its a goofy contraption and it took me about 10 mins to figure out how the vacuum even goes in it. lol Sadly someone rebristled it with nylon bristles from a toilet brush and they drag down the motor way too much to the point of smelling like burning wires, I need to figure out how to redo it with horsehair.