This product is a 7.83HZ very low frequency generator, with high precision and stability. Stable frequency acquisition elements: high stability pulse chip, precision correction capacitance, precision multi-loop adjustable resistance For more information, the Shumann resonance. For audio-visual space-to enhance the sound field and audiovisual effects For the bedroom-to help sleep relieve nerves, insomnia treatment For the Office: relax and improve work efficiency To create space-to enhance inspiration For the tea ceremony, the spiritual, the realization of space-Rest body and mind Frequency: 7.83Hz Nominal Voltage: 12V DC Nominal current: 1A Plug Type:EU Plug,it applies to Indonesia, Germany, France, Spain, Italy and so on. Colour:Black Material:plastic Size:122*92*31mm Package Contents: 1 * 7.83HZ Resonance Ultra-low Frequency Pulse wave Generator Anion negative-ion Generator Audio Resonator With Box 1 * EU 12v Power supply Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.