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. Note that the picture to the right shows the original design. The bolt to the left has been eliminated and the slot is in the end of each 1/3 section.