The left right angle iron plate of the range hood is balanced by the equipment running at high speed. Don't take it off, it will cause the fan to shake. Because of manufacturing reasons, the blades can't be 100% balanced in operation, so small iron plates can be used to balance the weight to reduce vibration and noise. Generally, you can't adjust it casually. If the blades are removed, the impeller will lose its dynamic balance, and the deflection of the impeller will become larger when it rotates, resulting in greater vibration and sound of the machine.