A caster (or castor) is a type of undriven wheel that is intended to be fastened to the bottom of a bigger object (the "vehicle") to allow for the movement of that object.
Usage
:Casters are used in numerous applications, including shopping carts, office chairs, toy wagons, hospital beds, and material handling equipment. High capacity, heavy duty casters are used in many industrial applications, such as platform trucks, carts, assemblies, and tow lines in plants.