Jim Cramer says he's urging investors to buy shares of aluminum producer Alcoa on a pullback. He calls Alcoa, which reports earnings next week, a multi-year story because chief executive Klaus Kleinfeld is transitioning the company from less of a commodity company to a proprietary one. Cramer reveals that what he likes most about Alcoa is that Kleinfeld breaks down every industry in which they sell, which covers many different areas as aluminum is so prevalent in our society. He says investors need to hear what he says about the world, as it's a great forecasting tool. Cramer calls Kleinfeld a great CEO and recommends buying shares of Alcoa if the stock gets hit.