Lee Oskar 1910-MAJ-LOW-D Major Diatonic Harmonica Maj Low DThe Major Diatonic Harmonica was originally intended for playing simple Folk music of the nineteenth century and its notation layout was adequate for that purpose. The Major Diatonic harmonica is the most commonly used tuning for playing Blues, Rock, Country Folk & Jazz. Several other manufacturers, using various names stamped on their cover plates, for marketing purposes, have the exact same notation layout as a Lee Oskar Major Diatonic harmonica.