A tube pan. Angel food cake is a special cake, so of course, it needs a special pan. That special pan is known as a "tube pan," and its two essential qualities are that a) it's round, usually without any decorative shape, and b) it has a hollow tube in its center. You can find it in both aluminum and carbon stainless steel, but TBH, both presentations are fine and fulfill their main purpose, which is to bake an angel food cake as soft as a feather.