The 03-zone tuning fork works at a frequency of about 78 Hz. It enhances the production of ozone in the body at a local area. The weighted fork can be used to wash over an area by pointing the prongs at it or the stem can be placed on a particular spot. The ozone layer is a layer in Earth's atmosphere which contains relatively high concentrations of ozone (O3). This layer absorbs 93-99% of the Sun's high frequency ultraviolet light, which is potentially damaging to life on earth. The O3 Forks enhance the production of ozone in the body at a local area. Benefits of Ozone: Ozone stimulates the production of white blood cells; inhibits the growth of new tissue; has a tendency to clear blockages of large and even smaller vessels; increases the flexibility and elasticity of red blood cells; increases immunity of human body. All our Tuning Forks are made from special grade Aluminium alloy and frequency is guaranteed to tuned to an accuracy of +/- 0.25% which is very good for healing