Features 7.8HZ GENERATOR --- Ultra low frequency Schumann wave generator, resonant frequency 7.8Hz (adjustable), with high accuracy and good stability. EXCELLENT PARTS --- Adopts highly stable pulse chip, precise correction capacitor and precise multiple loop adjustable resistor, with high reliability. LARGE CAPACITY --- Can be used after charging, the rechargeable large capacity lithium battery can last for about 400 days after being fully charged. MAIN PURPOSE --- Help people relax physically and mentally, improve perception of sound and images, reduce stress, and improve work efficiency. GOOD PERFORMANCE --- The generator adopts excellent PCB components to ensure stable performance, less interference and longer service life. Specification: Item Type: Schumann Wave Generator Material: PCB Resonance Frequency: 7.8Hz (Adjustable) Package List:1 x Schumann Wave Generator Package List 1 x Schumann Wave Generator