For maneuverability in tight spaces, these dollies have two platforms that swivel independently. Their casters are often called triple-swivel casters or zero-throw casters. Ball bearings between the platforms on these dollies allow you to turn and position the load without any caster movement. Made of polyurethane, their wheels combine the abrasion resistance of plastic with the shock- and sound-absorbing qualities of rubber. They’re also nonmarking. Use them on smooth or rough floors and in areas with debris. The top platform has slots for permanent mounting (fasteners not included).