COLSON Performa Casters roll quietly and easily, are very durable, protect floors and resist impact. Non-marking 1-1/4" wide gray thermoplastic elastomer tread is mechanically bonded to a gray polyolefin core with Delrin bearings. Swivel model has a double ball raceway with dust cover. Zinc plated finish with grease hole. Resistant to most chemicals, solvents, water, and acids. Total lock brake locks both wheel and swivel.