Consolidate your memory while you sleep Stimulates the brain into deep sleep Suitable for stabilizing the mind while meditating Suitable for improving inspiration when thinking Product size is compact and easy to carry Product introduction: This product is an electromagnetic wave that acts on the psychological perception. The human body has different sensitivities to the environment, that is to say, it also depends on the psychological perception. Therefore, the use and perception of the product are not intuitive. Physicists pointed out that the earth and the ionosphere form a resonant cavity with a very low frequency, and the resonant frequency is 7.83HZ. The wavelength of wave resonance frequency is just equivalent to the circumference of the earth, which is converted into a frequency of about eight to ten hertz. The human brain nervous system also have a coordinated response to the electromagnetic pulse frequency of wave to supplement the energy of human cells. Human health depends on natural energy and balance of body and mind. It is normal for each person to experience different results Colour:black Material:plastic Size:8.5 x 8.5 x 1.9cm Package Contents: 1 x host 1 x charging cable 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.