Secure your patio umbrella with ease using our 40lb. Round Black Umbrella Base. The base features a stem with adjustable collars. These collars accommodate a variety of umbrella pole sizes. Additionally, the stem includes a support knob to tighten and secure the post in place. This umbrella base is intended to be used alone, freestanding or with patio tables. Base is made of HDPE with cement inside.Features stem with adjustable collars.Compatible with several umbrella pole sizes.Knob to tighten post in place.Made from cement-filled plastic.For use with any 9' umbrella