I guess I think of crank-set as being the two crank arms, which generally come with rings, but I wouldn't be surprised in the least to see crank arms for sale as a "crank-set" without rings. As for what a couple others have mentioned, I don't expect it to come with a BB. In fact I'd be very(pleasantly) surprised to receive a BB with a "crank-set." In any case that seems like the person was intentionally playing word games unless there was a clear picture in the ad. Even then it seems a bit shady. I don't think I'd bother returning it, but mostly because it seems like the rings are the less important part compared to the crank arms. I wouldn't leave positive feedback, though. I'd leave none or neutral.