This ultra-low frequency Schumann wave generator can be used in your home to reduce your metal stress, also has a fine effect on insomnia, if you suffer from insomnia, you can try this product, it will not let you down. Features: The Schumann resonance (SR) is a set of spectral peaks in the extremely low frequency (ELF) part ) of the spectrum of the earth's electromagnetic field. This Schumann wave generator with high and precise stability, gives you a better using experience. You need to connect it to the power supply by type cable c, no battery included, which is convenient to use. You can use it in your home to reduce your insomnia, you can also use it in the office to improve work efficiency. It has a wide range of uses. Easy to use, you can use it directly after plugging in the power, whether you are a novice or an amateur, you can use it quickly. Features: Material: plastics Disc diameter: 82?mm/3.2?in Power supplies: type-c port Resonant frequency: 7.8 Hz (adjustable) Package size: 100*82*20mm/3.9*3.2*0.8in Package Weight?: 18g / 0.6 ounce Packing List: 1 * Schumann Resonance Generator