Schumann wave works on the space environment, helping people relax physically and mentally, improving the body's perception of sound and images, and may help with work efficiency and mental stress. Features: 7.83Hz ultra-low frequency Schumann wave generator with high accuracy and stability. Equipped with high stability pulse chip, precision correction capacitance, precision multi-loop adjustable resistor. Reliable polymer batteries with overcharge, overvoltage, overcurrent protection. Almost no voltage ripple in power supply. With work toggle switch for easy use. Suitable for HIFI or sleep. 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. Schumann wave for HIFI: 1. Suitable for systems with certain HIFI experience (equipment level not too low). 2. Can 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. For sleep: 1. Recommended to try one set, placed on bedside, over 1 meter away from human body. 2. Add appropriate weight for anti-vibration. 3. Use paper cloth to block indicator light 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: Package includes generator; power supply not included. This is a finished product, no assembly required. Color: As shown.