Polyolefin injected molded hard casters | Stain resistant | Chemical resistant | Non marking | Polyolefin injected molded hard casters^Stain resistant^Chemical resistant^Non markingGreenlee's 696 four-inch diameter casters are great for maintenance settings. You get two rigid and two swivel casters. They'Re made from polyolefin injected, molded hard rubber for durability. They are also stain resistant, chemical resistant, and nonmarking.