The Royal Dirt Devil series did have a few variations..
The Dirt Devil hand vac has been on the market for many years.
First models were all red and sported a 2.0 Amp motor. Model 103
At the same period of time was also the black and yellow series 500. Primarily I think this one was a just a color change to add competition between stores.
Later models of the handvac saw more changes. Some were 2 speed of the original style motor.
Later a red Plus Model came out with a larger sized hose port/ belt cover area and the rubber belt cover was attached to the machine so you didn't have search around on the floor for the round cap style one once a new belt was installed.
Also on the Red Plus Model series many had a 4.0 Amp motor which was much louder than the original more pleasant sounding motors.
There was a green plus series that was 2 speed and I used to own. It's motor was based off of the original motor and just offered a lower speed option.
I believe the latest Ultra model with the permanent attached hose and swing down door to block the suction is a 4 Amp. I've heard its quite loud.
The all blue model is technically a Royal Pro Series model. I do still have this one. It is a 2 speed with Royal name and the motor is of the original Dirt Series. It is model 533, 2 Amp motor.
I also do still own a Royal Prince hand vac. Amazingly quiet on that metal styled one!! The Royal Prince is Model: 501 with a 1.8 Amp motor and 25' cord.
Here's pictures of mine. I no longer own the green one.
