This 4" x 1-1/2” Soft Rubber Single on Kingpin Swivel Caster’s tread is formed over a solid rubber core. These wheels have a good shock absorbing cushioned ride, which offers floor conservation and a silent rolling operation. They come with a nylon bearing sleeve molded into the wheel core which offers enhanced roll-ability. These wheels are typically used on an ample amount of floor materials and cycle over obstacles, including elevator gaps, floor gaps, and cord with serenity.