What is the difference between a black ringed and silver ringed chainring crank? I'm pretty sure they are the same crank but does that indicate the model year, like 1985 for the black and 1987 for the silver? Was it part of a special edition? Also, on the back, if the crank is marked CA 170 compared to FC 170, I know they are both 170 mm but what does the CA or FC stand for? My other crank has CC 170 on it. Confusing me XD

On an aside, has anyone any idea of the Focus RG-700? I've never read anything about this bike and it has very decent components on it