Schumann wave works on the space environment, aiding physical and mental relaxation, improving the body's perception of sound and images, and contributing to better health and work efficiency, as well as relieving mental stress. Features: 7.83Hz ultra-low frequency Schumann wave generator with high accuracy and stability. Equipped with high stable frequency acquisition elements including stable pulse chip, precision correction capacitor, and precision multi-loop adjustable resistor. Built-in polymer battery with overcharge, overvoltage, and overcurrent protection. Minimal voltage ripple in power supply. Comes with a work toggle switch for easy use. Suitable for HIFI or sleep applications. Specifications: Model: CF-FM783-BA; Power: 5V android charging cable; Polymer battery capacity: 1400mah; Charging time: 6 hours (250mA charging current); Working current: 1mV; Working time: 200 hours (full charge); Size: 7 x 5.5 x 1cm / 2.76 x 2.17 x 0.39inch; Weight: 83g. HIFI Application: 1. For systems with certain HIFI experience (equipment level not too low). 2. May help perceive tone changes from different wires in the same system. 3. Recommended to try two sets for better effect. 4. Place on speaker with appropriate weight for anti-vibration. Sleep Application: 1. Recommended to try one set, placed on bedside, over 1 meter away from human body. 2. Use appropriate weight for anti-vibration. 3. Block indicator light with paper/cloth to remove night light. 4. Try for a week and analyze experience. Package Included: 1 x Ultra-low frequency pulse generator, 1 x USB cable, 1 x screwdriver. Note: Power supply not included. This is a finished product, no assembly required. Color as shown.