Polyolefin wheels are designed for hard impact and heavy loads! This wheel is injection molded from an exclusive CasterHQ polyolefin compound. Polyolefin wheels are very light in weight yet have a higher impact resistance than hard rubber wheels. These wheels offer superior resistance to grease, oils, chemicals, gasoline, acids, and animal fats. Caster HQ's polyolefin (plastic) wheels are also non-marking and provides zero water absorption for a far superior polyolefin wheel!Need Mounting Hardware? Click Here for high quality matching mounting hardware for your 4" x 4-1/2" Mounting Plate.