Casters are wheels mounted with an offset steering pivot that allows the wheel to automatically swivel to align itself to the direction from which it is pushed. They are often found on tool chests, shopping carts, rolling chairs, and other carts and cabinets. Casters work this way via a bearing above the wheel assembly that allows the wheel assembly to turn 360 degrees. Casters can be free swivelling, locking, have a limited turn radius, and can mount with either a stem or bolts, screws, and or a mounting plate. The wheels themselves are generally made of rubber of varying durometer, depending on the application.