Squared minus pi times the inner radius squared. Well, we already figured that out. The inner radius is 2 minus square root of y. And we're going to square that one too. So this gives us the area of one of our rings as a function of y, the top of the ring where I shaded in orange. And now if we want the volume of one of those rings, we have to multiply it by its depth or its height, the way we've drawn it right over here. And its height, we've done this multiple times already, right over here, is an infinitesimal change in y.