Casters feature dual grip ring technology that eliminates excessive noise for quiet mobility on all floor surfaces. Soft polyurethane material eliminates black powder residue created by metal-to-metal friction. Smooth-rolling wheels provide maximum mobility and smooth rolling. Soft wheel casters with a 120 lb. per wheel weight rating are designed for hard floors and chairmats.Casters feature dual grip ring technology that eliminates excessive noise for quiet mobility on all floor surfaces. Soft polyurethane material eliminates black powder residue created by metal-to-metal friction. Smooth-rolling wheels provide maximum mobility and smooth rolling. Soft wheel casters with a 120 lb. per wheel weight rating are designed for hard floors and chairmats.