Each of the 4 black plates are made from high-strength HDPE material that are rustproof and waterproof. This umbrella base stand is the best ideal for both residential and commercial location, our product will definitely match any of your outdoor, patio and garden. Approximately 350 lbs of holding weight when the umbrella base filled with water or an awesome350 lbs when filled with sand. Or even heavier when combined with both sand and water. Capacity: Up to 350 lbs when filled with sand and water (130 lbs of sand required).