The frequencies of Omnivos Solfeggio set are: 174, 285, 396, 417, 528, 639, 741, 852, 963 hz. This ancient scale is most often used to assist with healing deep emotional issues and creating an opening for heightened levels of awareness. ---- All Omnivos Tuning forks manufactured in the USA. To activate a tuning fork please use a hockey puck or tuning fork activator. A mallet restricts you from using several tuning forks at the same time. Our professional grade aluminum tuning forks are made of impact resistance aluminum making it approximately 26% harder and giving it a ring time up to 20% longer than other manufacturers. It has lower levels of impurities with the highest rating for surface finish per the Reynolds Aluminum Engineering Study. As are result, our material is more immune to corrosion and pitting. All of our forks are tuned to within .5% of the indicated frequency at 20 degrees Celsius, 68 degrees Fahrenheit and is subject to at least three inspection processes to eliminate imperfections. Other manufacturers tune to as high as 2.5%. Each tuning fork set comes with a carry bag.