A truck stop, known as a service station in the United Kingdom, and a travel center by major chains in the United States, is a commercial facility which provides refueling, rest (parking), and often ready-made food and other services to motorists and truck drivers. Truck stops are usually located on or near a busy road. Truck stop services Smaller truck stops might consist of only a parking area, a fueling station, and perhaps a diner restaurant. Larger truck stops might have convenience stores of various sizes, showers, a small video arcade, and a TV/movie theater (usually just a projector with an attached DVD player). The largest truck stops, like Iowa 80 (the largest in the world), might have several independent businesses operating under one roof, catering to a wide range of travelers' needs, and might have several major and minor fast-food chains operating a small food court. Larger truck stops also tend to have full-service maintenance facilities for heavy trucks, as well as vehicle wash services that can handle anything from passenger vehicles to large trucks. Some truck stops operate motels or have them adjacent. Most truck stops now offer separate fueling areas, often with dedicated entrances, for standard-sized passenger vehicles. The truck refueling area almost always offers dual pumps, one on each side, so large trucks can fill both tanks at once. (The second pump is referred to as the "slave pump" or "satellite pump.") The fuel islands at many truck stops can get very crowded. Most trucking companies have accounts with one or two truck stop chains and, after negotiating a specific price for diesel, require their drivers to fuel exclusively at supported locations. Truck stops near a large city, or on the east or west coasts, suffer from the most congestion at their fuel islands. The retail stores in large truck stops offer a large selection of 12-volt DC products, such as coffee makers, combo television units, toaster ovens, and frying pans primarily targeted towards truck drivers, who often spend extended periods of time on the road. Such shops generally offer a wide selection of maps, road atlases, truck stop and freeway exit guides, truck accessories (such as CB radio equipment and hazmat placards), plus entertainment media such as movies, video games, music, and audiobooks. Increasingly, as interstate truck drivers have become a large market for satellite radio, these retail stores also sell various satellite radio receivers