The items under consideration have been identified as the Ninebot Gokart Pro and the Ninebot S-Max. The Ninebot GoKart Pro is approximately 55.9 × 33.5 × 23.6 inches and weighs approximately 113 lbs. It can carry a single passenger up to 220 lbs. The Ninebot Gokart Pro is equipped with a single seat, a seat belt, a steering wheel with column, a tubular frame, bumper, front wheels, electric connection plugs, pedals, headlight, speaker, rear spoiler, assembly tools and a user manual. It is powered by 2 x 500-Watt electric motors. You state that the Ninebot Gokart Pro has various “modes” for speed: “ECO mode”, max. speed: 5 mph; “STRADA mode”, max. speed: 11 mph; “SPORT mode”, max. speed: 17.4 mph; and “CORSA mode” max. speed: 23 mph. The included manual states that it can travel up to 15.5 miles on a single charge. The Ninebot S-Max is a two-wheeled self-balancing hoverboard which serves as the rear drive motors of the Ninebot GoKart Pro that is capable of being detached from the main body and can be used independently from the go-kart body. The S-Max weighs 46.3 lbs. Has a maximum carry capacity of 137.4 lbs., a maximum speed of 12.4 mph and an approximate range of 23.6 miles on a single charge. You state that the Ninebot is powered by a lithium rechargeable battery. These two (2) items, designed to be connected and used together, form a composite good, with the Segway hoverboard establishing the essential character of the whole.
[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/N319331