Many devices have come and gone attempting to treat skin issues using frequencies. Many may automatically think of a high-frequency machine as an obvious choice, but these devices create ozone through frequencies. I believe this is actually harmful to skin because ozone causes free radical damage. For example, instead of considering acne a bacterial infection, it should be thought of as a detoxification reaction (and a delicate wound). Therefore, adding more inflammation to acne increases scarring potential. Other devices utilizing frequencies in the form of ultrasound can help with ingredient penetration, but high-frequency ultrasound (typically a medical procedure) can be harmful to skin and provide minimal long-term benefits.