This product is a Schumann 7.83Hz etremely low frequency generator, with high accuracy and stability.Highly stable frequency acquisition element highly stable pulse chip, precision tuning capacitor, precision adjustable multiloop resistor.Highquality polymer batteries, with overcharge protection, overvoltage protection, overcurrent protection. There is almost no voltage ripple in the power supply.With work switch, easy to use.The Schumann wave can be used for HIFI or sleep.Power 12V 1A Android charging cablePolymer battery capacity 2300mahWorking time 200 days fully chargedMaterial MetalColor blackPackage contents1 Ultralow frequency pulse generatorOnly the above package contents, other products are not included.Note Light reflection and different displays may cause the color of the item in the picture to be slightly different from the real thing. The measurement allowed error is 13cm.