Two Adjustable Knobs: With two manual knobs, the umbrella can be fixed to the base. The adjustable knobs in the steel tube can be tightened to ensure optimum strength and stability, regardless of the size of the umbrella pole Can be filled with water or sand: The base can be filled with water or sand up to 50 pounds and can be easily transported when emptied. The base does not include water or sand. Do not add water at or below 32°F to prevent freezing and cracking MULTIPLE UMBREllAS AVAILABLE: Multi-functional base is made of steel tubing, suitable for all umbrellas on the market, ideal for securing most umbrellas with pole diameters of Φ1.5" (38mm) to Φ1.9" (48mm) from 6-10 feet GOOD MATERIAL: Made of durable high density polyethylene material for all-weather use. The steel tube has good stability and will not allow the umbrella to tilt easily Wide range of application: Our beautiful and stylish base can be widely used in patio, garden, terrace, swimming pool, restaurant and other scenes Our round water filling base is suitable for home, villa, hotel, terrace, balcony, resort, water park, barbecue bar, western restaurant, beauty salon, outdoor recreation area, company recreation area, company resting area and so on.