Features: The pulses generator utilizes dsp synthesis technology for a stable and stability, ensuring confidence in use. Power by usb interfaces with 5v voltages and less than 1w rate power, operating at a frequency of 7.83hz for precise performances. The low frequency pulse generator is builts to last, ensuring accurate with excellent durability and wear for long-terms use Connect to external oscilloscope to observe waveforms or to external speaker for hand touch feeling waveforms vibration experience. Enhances physical and mental relaxation, improve perception of sound and imaging, and promote overall health with the generator. 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 Size:Approx.16.99x16cm/6.69x6.3inch Working Voltages: Dc5v Working Current:10ma Power Interfaces: USB (Supports USB Power Supply) Frequency:7.83hz Package Includes: 1pc Schumann Resonances Generator(without Shell) 1pc USB Cable note: Please allow 1mm errors due to manual measurement. Due to the differences between different monitors, the picture may not reflect the actual item color.