Two fine screw knobs adjust the tightness of the tube and securely hold the fishing umbrella. The umbrella mounting bracket has two screw knobs, which can adjust the tightness to fit. adapt to different sizes of umbrella handles to prevent the umbrella from falling. Suitable for umbrella handles with a diameter of less than 30mm. There is a slot on the board for easy mounting of the base, and screw knobs on the side of the tube help to tighten the base to the board. Great accessory for fishing enthusiasts, lightweight and portable to better fish with your hands. The umbrella holder securely attaches the umbrella to the tackle box. fishing, protecting you and your fishing gear from the sun and rain even on hot summer or rainy days. Umbrella Base Size (W*H): 70×50 mm / 2.76 × 1.96in Mounting plate size (L*W): 70 × 60mm / 2.76 × 2.36in Suitable for: Umbrella handle diameter about 30mm / 1.81" The adjustable umbrella holder is made of stainless steel, which is strong, anti-deformation,