Stroller has a different body structure for different purposes. Universal four-wheeled carts have a loading platform. For example, folding utility cart, with three-layer wire mesh fence plates trolleys, trolley, climb, wheelbarrows, platform hand truck, noiseless, their roles are different. Classification in accordance with the material, and can be divided into: stainless steel trolleys, steel trolleys, plastic trolleys, trolleys made of aluminum.