Specifically designed to fit under any Grosfillex 32 inch square and 38 inch round folding table and large 48 inch round resin tables. Must be filled with water or sand to weigh 35 to 40 lb. for stability. Made of 100 Percent prime resin, material naturally impervious to moisture, salt air, and chlorine. Built in resin glides will not stain, nor mar your terrace or deck. Two thumb screws to anchor the umbrella pole. Will not peel or rust in the hot sun. Easy to clean with soap and water.