The Combined Nomenclature (CN), v1:2018
9023 00: Instruments, apparatus and models designed for demonstrational purposes, e.g. in education or exhibitions, unsuitable for other uses (excl. ground flying trainers of heading 8805, collectors' pieces of heading 9705 and antiques of an age > 100 years of heading 9706)
https://www.dst.dk/en/Statistik/dokumentation/nomenklaturer/kn?id=bdccfab4-a71c-4f32-8b96-d3d9ed56013c