Features: 7.83HZ extremely low frequency pulse generators help to improve sleep, relieve fatigue. Low statical power consumption main intelligent chip is adopted, and the low frequency pulse is more stable. Output 7.83HZ pulse, with the characteristics of high precised and good stability. Type C power supply, connection to the power cord, the indication light is on and it is ready for use without any adjustment operation. It can improve the human body's perception of sound, improve the efficiency of work creation, and have a good effect on insomnial and mental stress. Specifications: Material: Plastic Size: approx. 10x8.2cm/3.94x3.23inch Name: Schumann Waves Generator Power supply: Type C port powered on Power: 1W Resonant frequency: 7.83Hz (adjustable around 10Hz) Working modes: 7.83Hz extremely low frequency electromagnetic Waves, no sound Package Includes: 1Pc Schumann Waves Generator note: This instrument is not rechargeable without a battery, simply connect it to a USB phone charging adapter, without current limit. Please allow 1-2cm errors due to manual measurement. Please allow for slight color differences due to different display resolution.