These LAG castors are made of pressed steel with heavy duty pressed steel forks. The swivel is hardened steel and have water resistant protections. The Polyurethane tyre rollers have high tear strength and abrasion resistance which gives them a life of up to 10 times that of rubber under similar operating conditions. Polyurethane is not affected by greases and mineral oils. Ideal for industrial use. Comes with either brown or blue polyurethane.