Feature: 1. Schumann waves 7.83HZ very low frequency generator features high accuracy and stability with MSDS certificate. 2. High stable frequency acquisition parts include high stability pulse chip, accuracy correction capacitance and accuracy multi-loop adjustable resistor. 3. And high quality polymer batteries is with overcharged, overvoltage, overcurrent protection. There is almost no voltage ripple in the voltage supply. 4. With work toggle switch, easy to use. Schumann waves can be applied to HIFI or sleep. 5. Rechargeable model, small and portable, comes with a 20CM charging cable. Newly optimized circuit designs and gold‑plated launching circuit. 6. Schumann wavse itself does not directly act on sound or video products to improve the quality of sound quality, but the role of the space environment, which relaxes people's body and mind, improves the human body's perception of sound and images, improves human healthy, improves work efficiency and mental stress with also has better results. 7. Used for audiovisual space, bedroom, office, innovative space, tea ceremony, space of realization to truth. Specification: Item Type: Ultra-low frequency pulse generator Size: Approx. 68 x 52 x 12mm / 2.7 x 2 x 0.5in (Length x Width x Height) Power Supply: 5V micro-usb for Android interface charging cable Battery: Polymer lithium battery, capacity 1200mah Use Time: Charging Current: 250ma Full Charge Time: About 6 hours Working Current: 7MA Full Charge Used for: About 200 hours (168 hours a week) Charging Cable: Approx. 20cm / 7.9in . Package List: 1 x Ultra‑Low Frequency Pulse Generator1 x USB Cable1 x Screwdriver Note: 1. Original imported core electronic components. It is recommended that multiple units be used in a distributed manner, the effect can be more felt.2. Do not tear off the protective film, disassemble and touch the components individually when the product is on trial. The high stable frequency is strictly adjusted and tested by the factory.3. Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.