These are the parts that hold the end of the Flex Shaft on the outside of the Hull. The longer piece with the hole in the middle fits on the transom inside the hull. One piece slides over the Flex Shaft and then slides between the piece that attaches to the outside of the transom. The inside and outside pieces screw together through the transom.
The Rudder assembly also screws directly into the other end of the Inside piece of the Strut Support. The metal rod that runs from the Servo to the Rudder run through the hole in the middle of the inside Strut Support.