yes they do replace both the spring and the strut (shock, damper, whatever) and the adjustability makes them very nice for getting the car "dialed-in" just right to your liking. they do cost quite a bit more but the adjustability is the key to a true coilover system.

side note: just a little tip for the future, please make sure you use full words and punctuation. the teenie bopper aol'er speak is really annoying to most of us here, Especially those of us that are able to give the biggest help.