Induces growth of one or two additional fully functional fingers on each hand, positioned between the ring and little finger. The extra digits have full skeletal, muscular, tendon, and neural integration — they're not vestigial; they work. The brain's somatosensory and motor cortices must expand to accommodate the new digits, which requires a neural integration period of 3–6 months during which the extra fingers are clumsy and poorly coordinated. Users who complete integration report that the extra fingers feel natural — they can't imagine having only five. The modification is valued by musicians, surgeons, craftspeople, and anyone whose work benefits from additional manual dexterity. Six-fingered and seven-fingered pianists can play chords that are physically impossible for five-fingered hands. Zheng-Dao Bioelectric's installation is the gold standard, with the fastest neural integration time.