Grahikum Small Metal Castor Wheel for Robotic Projects(Pack of 2) Educational Electronic Hobby Kit

A caster wheel is a driven, single, double or compound wheel that is designed to be mounted to the bottom of a larger object, so as to enable that object to be easily moved. They are available in various sizes, and are commonly made of rubber, plastic, nylon, aluminum or stainless steel. The outer diameter of a caster wheel affects how easy it is for the caster to be able to move across rough or irregular surfaces. Large diameter caster wheels are able to bridge wide gaps where a small caster would fall inside and get stuck, such as the gap in the floor between an elevator door and the elevator car.