Features: Using ABS materials, the product have good frequency stability. This product not only outputs 7.83Hz Schumann waves, but also incorporates programmable frequency modulation technology, which can adjust the frequency in the ranges of 0.1HZ-100000HZ. The power interfaces adopts DC5.5x2.1 interfaces, which is convenient to use. Schumann waves themselves do not directly act on sound or video products to improve sound quality, but rather on the spatial environment, relaxing the body and mind, improving the body perception of sound, improving the efficiency of human health work, and relieving psychological stress. The digital circuit crystal oscillator frequency reference is more stable and have strong antiinterference ability. The product is plug and play. When the frequency is high, there will be a deviation of less than 1%between the input and the actual output. The sound output of the speaker is based on the frequency. At low frequencies, the human ear cannot hear it. If the speaker is plugged in and the frequency reaches the hearing ranges, there will be sound. Specifications: Component:ABS Power supply interfaces: DC5.5x2.1mm Power supply voltages: 5V Power consumption: <1W Frequency: 7.83Hz Adjustment ranges: 0.1Hz-100000Hz voltages amplitudes of sine signal: 3.0V voltages amplitudes of square Waves signal: 5V Size:Approx.20x14cm/7.87x5.51inch Package Includes: 1Pc Schuman Waves Generator note: 1.Please allow 1-2cm errors due to manual measurement, making sure that you not mind before order. 2.Due to the differences between different monitors, the picture may not reflect the actual of the item.