Wow, your putting some thought into this ;) It's actually a hydraulic actuating cylinder retained in the body cavity by the bolt pattern used to store the outer tension ring assembly in a profile when not in use. The twelve yoke assemblies actually have wire hydraulic tensioning assemblies connected to them for a total uplift capacity of 1,900,000 lbs force. The bulk of the unit is coated with a three part marine epoxy paint system and the cylinders you pointed out are coated with xylan to inhibit corrosion but is now being coated with sermagard as it has better UV resistance.