This product is Schumann wave 7.83HZ very low frequency generator, features high accuracy and stability. High stable frequency acquisition elements: high stability pulse chip, precision correction capacitance, precision multi-loop adjustable resistor. High quality polymer batteries, with overcharged, overvoltage, overcurrent protection. There is almost no voltage ripple in the voltage supply. With work toggle switch, easy to use. Schumann wave can be applied to HIFI or sleep. : 12V 1A android charging cable Polymer battery capacity: 2300mah Working time: 200 days(full of electricity) Material: Metal colour: black Package Contents: 1 x Ultra-low frequency pulse generator 1 x English manul Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.