Introducing the Suzuki Tonechimes 4th octave expansion setThis is a smaller, expansion set of hand chimes which has been created to work in addition to the HB-250. HB-12A 3rd octave expansion kit sets of chimes.The HB-250 is the core set of 25 notes which encompass G4 - G6. The HB-12A expands this set at both the bottom and the top. The HB-12B further expands these two sets at the bottom, G3 - B3 and at the top C#7 - G7.It is important to remember that this HB-12B set is designed to complement the HB-250 and the HB-12A and is not necessarily something to purchase as a standalone product.As with all Suzuki Tonechimes, quality is superb with a bell-like tonal resonance and a lightweight construction. They are also supplied in a solid protective hard case.