These have been amazing! I've often used tone generating apps for the Solfeggio frequencies, but using the tuning forks improves upon that drastically. Having something (other than the tiny speakers in one's tablet or phone) actually vibrating at these frequencies seems to boost the intensity of the frequencies themselves! Plus, they don't require any electricity, and have been pleasantly portable--a good bonus for meditating out in nature without your phone/devices around to distract. ;) Definitely glad to have made this purchase.