This square water tank base, made of high quality black PP material, is durable and weather resistant, suitable for long-term outdoor use. It can be filled with water or sand to increase the weight, and the weight of the base can be up to 20KG after filling, which provides stable support for the umbrella and prevents it from tipping over to ensure the safety of use. The inner diameter of the base is suitable for umbrella poles with a diameter of 38mm, which is widely applicable and easy to install. Whether it is a patio umbrella or outdoor leisure umbrella, this water tank base can be perfectly adapted to add a peace of mind and stability to your outdoor space. Its simple square design is aesthetically pleasing and complements a variety of patio styles, making it an ideal choice for outdoor recreation. Dakota Fields