How many did YOU know! At the bottom is a Eureka built Wards tank,from right to left is a Royal, the the most powerful of them all.."In My humble opinion!" an Apex 603!! This is the one made like a Royal handvac, the motor is in a seald chamber and the dirt goes AROUND it and into the bag, if you have never got to see one of these it is really something, it will literally lift a good sized throw rug off the floor!, Next is a Premier, then the Hoover 61 I think,then a GE and then.."Oh RICK!!!" a Universal!, then Eurekas 2 cleaners, the upright from which all later Eurekas came and the tank, the early version of which was cardboard!