S-Builder works like this: We essentially pool the advertising dollars of hundreds of SFI affiliates and then place ads on their behalf. Everyone participating in the co-op then shares in the results of the advertising. Pooling money like this allows us to purchase blocks of advertising that would be too risky for individuals. As a major media buyer, it also means we can get volume discounts on the advertising we buy for the co-op (i.e. we can deliver more "bang for your buck.")