The side post umbrellas stainless steel foot is a fixed part of the xxl side post umbrella. The sheet is mounted to to a concrete plinth which should not be smaller then 1 m x 1 m x 50 cm (3' feet 3" inches square, 1' feet 8" inches depth) to provide the necessary grip. Optional available: Stainless steel sheet 1 m x 1 m x 50 cm (3' feet 3" inches square, 0.39" inches height) for additional stability.