Features: Brand new and high quality This Schumann waves generator is 7.83HZ very low frequency generator, which features accuracy and stability. The metal material ensures its durability, precisions with a long service life The Schumann generator adopts stable frequency acquisition including stability pulse chip, precisions correction capacitance and precisions multiloop adjustable resistor, in order to ensure the reliable performances of this product This Pulse Generator is adopted with polymer batteries, with overcharged, overvoltage, overcurrent protections. There is almost no voltage in the voltage supply The Schumann waves can help create relaxed atmosphere, making people calm and comfortable. It helps to improve sleeps quality, relieve fatigue and restore physical and mental health. With work switches, this Schumann generator is easy to use. Specifications: Material:Metal Size:Approx.68x52x12mm/2.67x2.04x0.47inch Power supply: 5V Battery: 850mah Charging current: 250ma Charging time: 3-4hours Operating current: 7MA Usage time: 100hours Package Includes: 1x Schumann Waves Generator note: 1.Please allow 1-2cm errors due to manual measurement, make sure that you do not mind before you order. 2.Due to the difference between different monitors, the picture may not reflect the actual color of the item.