In its turn, CPO delivered means fixed payments just for the fact of placing an order. One more example: webmaster runs traffic, traffic leads some potential customers, then there are placed orders, but call center do not call anyone in order to confirm. BUT when the order is delivered to the customer, webmaster is paid his fixed fee. By the way, in this scenario the web's statistics on the redemption percentage plays a significant role: if it is high, then this is a very significant argument for an advertiser for making a payment. A small percentage will make the advertiser think in the opposite direction.