- Key of C - 10 hole harmonica - With high quality brass reed plates - Incl. hard plastic case and cleaning cloth - Easy to play - Great sound characteristics - Perfect for beginners to advanced players The Cascha Blues Harmonica is perfect for beginners through to advanced players. It’s always handy and you can learn to play it quick and easy. The Harmonica is tuned in the key of C, which is the most common and most used tuning of harmonicas. It’s a suitable instrument for either solo ...