The Treasure Garden 50 lb. Umbrella Base has an adjustable 17.5" dual purpose stem made up of 6.5" and 11" lengths that allows it to transition easily from free-standing applications to under-table uses. The 1.5" stem has two height positions and is also available in an optional 2" pole diameter model. Full stem is ideal for free-standing shade applications. Reduced stem is for under-the-table applications. It has a cast aluminum exterior with a cast iron core. For extra weight needed for larger patio umbrellas or free-standing umbrellas, there is a 30 lb. add-on weight available. The add-on weight screws effortlessly onto the underside of the Garden Base. Diameter: 19.3"Weight: 50 lbs Material: Cast Iron DUAL-PURPOSE STEMBase stem fits umbrella poles up to 1.5".Ideal for free-standing or positioned under-the-table. ADD-ON WEIGHTOptional cast iron 30 lb. weightthat can be added onto our 50 lb. base.