Plow & Hearth Aluminum Market Umbrella Pole Stem Adapter Umbrella pole stem adapter Allows larger umbrellas to fit weighted base Holds umbrellas sturdy within base Use with our 11' deluxe market umbrella and 50 lb. Cast iron umbrella base (Sold Separately) Works with other umbrellas that have 1-7/8" dia. and larger poles and bases that have openings less than 1-7/8" dia