You have to be more specific as to which one you are talking about. They have two dampers which are red. One is the STR.T, which is the new entry level Koni shock, about as good as HP series from Tokico, and GR2 from KYB. They also have Special D, which I can't believe they still carry. It's a sport damper, which they've been building forever, and while it is adjustable, you have to take it off the car to do so.
Yellow damper could be either single adjustable (rebound only) or double adjustable (bound and rebound). I've been running Single Adjustable for well over two years now, and they are still working well for me. One good thing I really like about Yellows is that even on full soft setting, they still control the spring motion much better than factory dampers, and most entry level dampers. That's the setting I use on the street, and the ride quality is actually very good for how stiff the springs are, and how little give there is in bushings.