These programs allow trades with other resort units in different locations for an additional fee. However, these trades usually cannot be guaranteed. There also may be some limits on exchange opportunities. Most developers are affiliated with large exchange companies. Two major companies are Resort Condominiums International (RCI) and Interval International (II). When a developer affiliates with the exchange company, the exchange company allows all of the buyers who purchase at that development to be able to join the exchange company. The developer pays an initial fee to the exchange company, and thereafter the individual timeshare owners are usually assessed an annual fee. The exchange company provides owners with a directory of hundreds of resorts. The exchange company is a huge computerized reservation system that is also licensed as a travel agency. An individual can deposit the week that they own and trade it for a week at another resort anywhere in the world, provided that one is available. There is usually a fee for the exchange, and there are also size rules, which allow trades equal or down. In most exchanges, a two bedroom can exchange for a two bedroom, but a three bedroom would likely require additional charges. Both of the major exchange companies rate their resorts. Usually, one needs to be giving up a week at a top resort to get a week at another top resort. In RCI the top rated resorts are called Gold Crown. In II top resorts are known as Five Star. There are a number of smaller exchange companies that are available to timeshare owners. These smaller companies are often regionally based.