The Major Diatonic harmonica is the most commonly used tuning for playing Blues, Rock, Country, Folk and Jazz. This is the traditional blues and rock harmonica tuning. Major Diatonic harps are produced by several manufacturers and all of these harmonicas have the exact same note layout as the Lee Oskar Major Diatonic. The most important difference is in the quality of materials, construction, design and sound. Lee Oskars are the best harmonicas in the world, andthat's not just our opinion. All over the world, professional players prefer Lee Oskar Harps over any other brand.