radio control. This external control can also be used to limit young riders to a slow operating speed, while a race consisting only of adults is permitted a higher speed. These controls can be applied to both electric and combustion-engine karts. In some countries, go-karts can be licensed for use on public roads often referred to as street tracks. Typically there are some restrictions; in the European Union, a go-kart modified for use on the road must be outfitted with headlights (high/low beam), tail lights, a horn, indicators, and an engine not exceeding . Recreational, concession and indoor karts Besides traditional kart racing, many commercial enterprises offer karts for rent, often called "recreational" or "concession" karts. The tracks can be indoor or outdoor. Karts are rented by sessions (usually from 10 to 30 minutes) or on a day basis. They use sturdy chassis complete with dedicated bodywork, providing driver safety. Most of these enterprises use an "Arrive and Drive" format which provides customers with all the safety gear (helmets, gloves and driver outfits) necessary, and allow them to show up anytime to race at a reasonable price, without the problem of having to own their own equipment and gear. Outdoor tracks can offer low-speed karts strictly for amusement (dedicated chassis equipped with low powered four-stroke engines or electric motors), or faster, more powerful karts, similar to a racing kart, powered by four-stroke engines up to and, more rarely, by 2-stroke engines, but designed to be more robust for rental use. Typically, outdoor tracks are also used for traditional kart races. Indoor kart tracks can be found in many large cities in different parts of the world. These tracks are often located in refurbished factories or warehouses, and are typically shorter than traditional outdoor tracks. Indoor karts are usually powered by a four-stroke gasoline engine producing anywhere from , or sometimes by an electric motor. Many tracks offer competitive races and leagues. At the top level, an Indoor Karting World Championship (IKWC) exists. See also Model car References zh-yue:高卡車 Sports cars Convertibles