2" (50mm). Twin wheel stem. Black, soft tread. Twin wheel casters place more wheel surface on the floor surface. Wheels move in opposite directions to minimize carpet fiber twisting. For use on ready-to-assemble furniture, office chairs, printer stands, entertainment centers, and computer desks. Plate measures 1-1/2" x 1-1/2". Not recommended for use on hardwood and laminate flooring Load capacity: 75 lb. 2 per card.