This product is a Schumann .83HZ extremely low frequency generator with high precision and good stability. High-stable frequency acquisition components: high-stable pulse chip, precision correction capacitor, precision multi-loop adjustable resistance It can enhance the sound field and audio-visual effects, help to soothe the nerves during sleep, treat insomnia, the mind, and work efficiency Schumann wave itself does not directly on sound or video products to sound quality, acts on the space environment to people's body and mind, the human body's perception of sound and images, and human health. It is also good for improving work efficiency and mental stress. colour: as shown Material: ABS Package Contents: 1 set x Schumann wave generator(With housing, need to install by yourself) 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.