These xylophones feature rosewood tone bars, natural finish wood boxes, two extra F# and one Bb bars with diatonic units. Lyons xylophones are designed with both quality and economy in mind. These instruments begin with solid wood tone boxes, then add hand-tuned rosewood tone bars to combine for rich warm sound. All Lyons tone bars are backed by a lifetime tuning warranty. chromatic add-ons are separate tone boxes with the sharp/flat key to be used with a diatonic unit to have a fully chromatic set.Tone bars Natural finish wood boxes Two extra F# and one Bb bars with diatonic units