The Shepherd Hardware Polypropylene Casters are lightweight, non-marking wheels that are impervious to water and have strong chemical resistance. These casters are a long lasting, economical alternative to other industrial caster materials. Shepherd Hardware has an expansive line of polypropylene casters with a variety of options and sizes to fit all caster needs. The Shepherd 9799 model features a 4 inch diameter wheel, and a 275-lb load rating.