Hand-turn knob design: The round base design of this product is solid enough to hold the umbrella. A hand-turn tightening knobs on the hole for securing an umbrella to the base. Suitable for two kinds of outdoor umbrellas with conventional tube diameter 38mm/48mm in the market. Simple assembly: For more convenience with this round plastic base stand , it includes detailed assembly directions to make installation a breeze. So you can set it up with no fuss. Outdoor umbrella essential: Suitable for umbrellas when used through an outside garden table or freestanding in a wind-free position. Provides a solid base for compatible umbrellas.