umbrella base W640P245801Filled with Water Sand: This round umbrella base can be weighed with 42 pounds(each piece) of sand or 11. 3 liters of water(each piece). You can also mix some water and sand to increase weight STURDY 4 PLATE DESIGN: Four Piece Detachable Square Umbrella Base Weight Plates, Perfect for Most Types of Cantilever Offset Patio Umbrellas, Providing Extremely Stable Support. (Note: Crossbar base not included) EASY FILL & WATERPROOF SEAL: Each plate is built