Some fan shells are not as stiff as they need to be. I have a steel ring to correct that. Below are shots of the ring installed. All that is needed is 6 self tapping screws to position the ring. Put 3 self taps in place at about 120 degrees apart and about 2 inches from the blade on the opposite side from the motor. Then put the ring on the 3 screws and extend the slots until the ring is tight against the shell all around. Tighten the bolts to hold the ring stiff. Then install 3 more self taps above to hold the ring in place.