High Quality Material: Made of 600D oxford fabric, waterproof and durable and will last for years to come. Sealing Device: Each bag comes with Sealing Devices which make filling easier sand, gravel, or other suitable contents. Square Design: Holds up to 110 lbs of sand to ensure the umbrella or flagpole remains stable in wind, storm and other inclement weather. Easy to install: 2 weight bags have a unique design for easy installation and use. Widely Used: Suitable for all racks. cantilever patio cantilever, classic table designs and all standard size pillars.