Identifying light, reg, heavy Super Speeds??

I am sure there is probably already a post for this, but 1950s era Gillette ads refer to three different grades of Super Speed razors. See an example here ...

http://www.youtube.com/watch?v=H-gmoyG2PT8

Is there any markings on the razors which identify whether they are light, regular or heavy??

It's all in the flair tip. Blue for light, plain chrome for regular, and red for heavy.

this Ad shows all 3:

Thanks! I was pretty sure it was something simple and figured I'd get a quick answer here. I wasn't sure whether the colors of the tips changed with different model years, or was the key to the aggressiveness.