Baggage carts, luggage carts, luggage trolleys or trolleys are small vehicles pushed by travelers (human-powered) to carry individual luggage[citation needed], mostly suitcases. There are two major sizes: One for big luggage[clarification needed] and one for small luggage[clarification needed]. Carts have usually two parts for carrying luggage: A small section (basket) for carry on luggage at the same level as the handle, and a lowered large section for suitcases a small and large bags.[citation needed]The baggage cart was invented by supermarket entrepreneur and inventor of the shopping cart Sylvan Goldman.[citation needed]The carts are provided in airports, large bus stations,[citation needed] hotels, or train stations for transporting luggage and may be free of charge. They are sometimes owned by the operator of the establishment. In some facilities carts may be provided by a contractor such as Smarte Carte for a rental fee. Baggage carts are usually built out of steel and equipped with three or four wheels. For safety reasons, they are generally fitted with a brake.[citation needed] Usually, a handle has to be pushed down in order to move the cart, however, in some cases, such as London airports, the handle activates the brake. Very few carts, e.g. in developing countries such as Sri Lanka, do not have this feature.[citation needed]In systems with a rental fee a portion of the rental fee may be returned when the cart is returned to the rack.