Capacity 20,000 pounds per caster under ideal operating conditions. Load ratings are based on manually moved loads at a speed up to 3 mph under ideal operating conditions. If your application involves abuse please contact us for a recommendation. Consult us for a capacity rating based on your application if these casters are to be used with mechanically powered equipment.  This caster uses 4 inch wide wheels that are 8, 10, or 12 inches in diameter. Model 150 has the largest top plate and thickest legs of any of our caster brackets which allow for the heaviest loads and the most arduous service. When used with mechanically powered equipment please consult us for a recommendation.