This schumann waves ultra-Low frequency generator can be used in yor home to reduce your metal stress, also has a fine effect on insomnia, if you are suffering from insomnia, you can try this product, it will not let you down.Features:Schumann resonance (SR) are a set of spectrum peaks in the extremely low frequency (ELF) part of the earth's electronmagnetic field specturm.This schumann waves generator with high precise and fine stability, give you a better using experience.You need to connect it with the power by type-c cable, no battery included, which is convenient to use.You can use it in your home to reduce your insomnia, also can use it in the office to improve work efficiency. It has a wide ranges of uses.Easy to operate, you can use it directly after plug in the power, whether you are a novice or an amateur, you can use it quickly.Specifications:Material: plasticsDisk diameter: 82mm / 3.2inPower supplys: Type-c portResonant frequency: 7.8Hz (adjustable)Package size: 100 * 82 * 20mm / 3.9 * 3.2 * 0.8inPackage weight: 18g / 0.6ouncePacking list:1 * Schumann Resonance Generator