Well, it's a later Duplex. Probably from the mid '30's. Older Duplexes had a single wheel on either side of the nozzle. I found mine in the garbage and it has the two side wheels. This is the first I've seen with "Premier Special" written on the bag. It could well be that it was refurbished in house by Premier (ala Hoover Special). I have an Air-Way Sanitary System like that. Does it say anything on the manufacturing plate about being refurbished?