Check the listing for details. Adjustable Frequency Generator 0.01Hz-200kHz for Sleep, Yoga, Meditation,. Color: White, Condition: New. Listed at 48.53 USD. Experience versatile frequency generation with this compact device. Designed for modern convenience, the device includes a USB Type-C port for straightforward power connection. 【7.83Hz Improve Your Sleep】Harness the natural rhythm of the Earth with our high-quality Schumann resonance generator.