Aircraft Gimbal, which is a part of an aircraft ducting system. It enables 5 to 8.5 degrees angulation to direct the flow of air through aircraft parts, including but not limited to diverting air from the aircraft engines and auxiliary power units. The aircraft gimbal is a circular connecting device ranging from 1 to 9 inches diameter, weighing 0.75 to 2.0 kilograms. The aircraft gimbal is welded into titanium duct assemblies that make up the ducting system and can be attached at either end or variation throughout the ducting system.
[1] Please importantly note that only the relevant portion of the related is displayed above. You may refer to the said customs ruling for the entire ruling explanation.
[1]. https://rulings.cbp.gov/ruling/N299432