World's Smallest HarmonicaA quality miniature harmonica thats perfectly playable from beginner to expert. Plays in the key of C. The harmonica has a metal cover and base plate and creates a surprisingly loud note. Worlds smallest harmonica. 4 Hole, perfectly playable harmonica, transformed into a keychain. Attach it to your keys and surprise your friends with a fun tune on the go. Anyone can pick up and play, from beginner to expert. When played, creates a surprisingly loud