This 17.5" heavy-duty round umbrella base is ideal for holding your beloved umbrella to beautify your surrounding environment. Â This is our 17.5" square umbrella base which is ideal for holding your umbrella securely and evenly in place. It is a really practical addition to your backyard or your patio area. Includes a coupler to allow it to fit 38mm to 48mm (by removing the adapter) in diameter umbrella poles. Includes a hand-turn knob for securing the umbrella to the base. Â Don't hesitate to