High Stability: This Schumann wave generator is made from highly stable pulse chip, accuracy correction capacitance, and accuracy multiloop adjustable resistor. Physical Relaxation: This ultra low frequency pulse generator is good for people's physical and mental relaxation, improve the body's perception of sound and images. Pressure Relief: This 7.83HZ pulse generator contributes to improve work efficiency and reduce mental stress. Easy to Use: This ultra low frequency pulse generator with Type C interface is easy to use. and it features high accuracy and stability. Perfect Gift: Schumann wave generator is perfect gift for friends and family that suffer from insomnia and mental stress. Material: PC + metal colour: As Shown Package Contents: 1 x schumann wave generator 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.