How big is the mail car suitable for children to play with?

4-8 years old. "Mail Car" is a piano music with simple melody. The overall melody is easy to master, the notes are simple and clear, and the basic requirements for piano are low. It is suitable for piano beginners aged 4-8. "Mail Car" is a title song created by German composer Herman Nick. The music is cheerful and lively, with the rhythm characteristics of March. This paper describes the whole journey of the mail car until it reaches its destination.