1. This product is made of high quality materials, the use of low temperature drift crystal oscillator and high precision special chip, the product has good frequency stability 2. This product can not only output 7.83Hz Schuman wave, but also add programmable frequency modulation technology, can adjust the frequency in the range of 0.01Hz-30000Hz 3.2 kinds of specifications, there are 2 kinds without shell and with shell can be selected according to demand 4. Digital circuit crystal frequency benchmark, more stable, stronger anti-interference Schuman wave itself is not directly acting on sound or video products to improve the sound quality, but the role of the space environment, so that people's body and mind can be relaxed, improve the body's perception of sound and images, improve the health of the human body work efficiency, relieve psychological pressure also has a good effect. The product can not only output 7.83Hz Schumann wave, but also adjust the frequency in the range of 0.01Hz-30000Hz, digital circuit crystal oscillator frequency reference, more stable, stronger anti-interference, using low-temperature drift crystal oscillator and high-precision dedicated chip, can precisely output frequency and pure sine wave. Working voltage: DC 5V Default frequency: 7.83Hz Adjustment range: 0.01Hz-30000Hz pure sine wave Signal voltage amplitude: 3V Due to different batches, there may be differences in product appearance and printed text, which will not affect use Colour:As Shown Material:PCB Type: No shell/With shell Package Contents: 1 x Schumann Wave Generator with line Only the above package content, other products are not included. Note: Light reflection 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.