1、High Strength: This stroller assembly middle support is made of solid steel, which is high strength and impact resistant and galvanized zinc plated for rust resistance. 2、Stable Operation: The wheel trolley case is mounted with standard deep groove ball bearings, which are very sleek and noiseless when in use. Welded bearing positioning ensures working stability. 3、Impact Resistant Head: In order to prevent strong impacts from damaging the wheels, the trolley assembly has been thickened with impact resistant parts. 4、Multi Layer Plating: This cart assembly utilizes multi layer plating to provide effective protection to the wheels and increase the acid, alkali and erosion resistance of the wheels. 5、L Shaped Removable Insert Design: This trolley assembly is designed with L shaped removable inserts for quick installation and easy removal.