Shop for Bases and Stands from PatioUmbrellas.com! The Oxford Garden Market Umbrella Table Clamp is designed for use exclusively with Oxford Garden round patio dining tables. Mount this clamp to the cross brace of any of these round dining tables to adequately anchor your umbrella. The clamp is constructed of heavy-duty steel features a black powder-coated finish and fits umbrella pole up to 1.5-inches diameter.