Cast Iron is the standard metal wheel used by most unless a heavier capacity or greater impact strength metal wheel is needed. For applications requiring more capacity or impact strength, check out the ductile steel & forged steel wheel caster options. Please note that all 2" wide wheels are heavy duty cast iron & come with thicker treads, stronger spokes, & larger hub diameter compared to the standard cast iron.Whilecast ironis very strong, it is tough on floors and could lead to floor damage. For heavy duty floor protective wheels, be sure to check out our polyurethane wheels.*Please note temperature ratings are dependent upon the bearing selected. Unless noted otherwise in the options, bearings will have a 180??F temperature rating.