Not sold on the BIRGing idea yet? Take, then, the fact that the teams with the best-selling sports apparel traditionally are the most successful. Over the past five years in the United States, gear for the New York Yankees, the Miami Heat, and the San Francisco 49ers has been very popular in national sales for baseball, basketball, and football, respectively. Not surprisingly, these are among the winningest teams in the last five years.

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