The 24" square outdoor umbrella base stand is made of selected heavy-duty steel with a powder-coated surface. Â Thus this umbrella base is weather resistance and rust resistance allowing you to use it outdoors all year around. Moreover it is equipped with 2 adapters to fit different umbrellas with a diameter of 1.6" or 1.9" and you can use the 2 adjustable tightening knobs to secure the umbrella pole preventing it from wobbling or falling. More importantly this umbrella base comes with 2 built-i