Wanda 6"x2" cast iron and semi steel wheels casters are made of incredibly strong steel that is highly resistant to abuse and tough environments. Cast Iron wheels are able to withstand high temperatures and can be exposed to water and/or other abusive factors in challenging environments. They can withstand exposure to chemicals, grease and oil. However, one downside is that Cast Iron wheels will rust over time if exposed to fluids and chemicals regularly. High Load Capacities (Up to thousands of lbs depending on wheel size), High Heat Resistance (-45F to +500F), Resistance to liquids and chemicals, Multiple styles of bearings available