A disadvantage to credit cards is that merchants must pay a significant transaction fee of from between 3% and 5% of the sale. The risks of a transaction, as mentioned above, are largely borne by the merchant. In addition to the percentage fee, merchants must also pay an additional transaction fee of 20-30 cents per transaction as well as other set-up fees. The high transaction costs make selling small items such as articles and music tracks undesirable on the Web. Furthermore, online merchants never see the actual card being used, no card impression is taken, and no signature is available. These last three reasons are why consumers can later dispute charges. The merchant faces the risk that transaction will be refuted and reversed even though the merchandise has already been shipped, or the digital product has already been downloaded. Existing credit card payment systems also offer poor security because neither the merchant nor the consumer can be fully authenticated. Requiring a credit card for payment also discriminates against some consumers because millions of young adults and almost one-hundred million Americans who cannot afford credit cards are denied access to online shopping.