This 6" x 2" flat tread thermoplastic rubber premium heavy duty swivel caster provides smooth and quiet operation. They are safe to use on all floors.Our 44 Series casters are our most popular 2-inch wide industrial mobility solution. 44 Series caster rigs are manufactured in the United States, for expedited shipping and increased quality assurance. Many wheel options are also made in the US. Zinc plating provides an attractive finish which increases corrosion resistance and provides longer caster life.