Harmonic spectrum 8 pc set contains a full octave of tuning forks (C, D, E, F, G, A, B, C). They create a series of overtones to help you relax and center yourself. Each interval relates to a different state of consciousness and body posture. Each interval affects your nervous system in a different way by activating specific elemental qualities. Chakra Set are another set of forks that can be used with the Chakra. This set consists of 7 forks and unlike the Harmonic Spectrum, which is tuned to the Pythagorean Scale (also known as the Just Scale), these forks are NOT based on a musical scale. They are based on the mathematical rotation of the planets around our Sun. The Chakra Tuning Forks work more on the cosmic multi-dimensions of our chakras, our subtle bodies and other energy gateways & pathways. This precision set of 11 tuning forks is calibrated to the tones of the Sun, Moon, Earth, Mars, Venus, Jupiter, Neptune, Mercury, Saturn, Uranus, and Pluto. The exact tones were calculated by Hans Cousto, the Swiss mathematician, using an octave based on the time for planets to revolve around the Sun. These tuning forks are specifically tuned with cosmological and astronomical timing. Includes Sun (transcendence), Moon (sexual energy), Earth (relaxation & meditation), Mars (creativity, will power, masculine), Venus (love, harmony, feminine), Jupiter (art & creation), Neptune (intuition & dreams), Mercury (communication & voice), Saturn (concentration & awareness), Uranus (spontaneity & openness), and Pluto (group & interpersonal integration).