What is the high frequency? The direct high frequency increases the activity of the basal layer of the skin, improves the texture of the skin, and improves the skin's defense against bacteria. OUR GUARANTEE We are confident that we offer some of the best products on the market. Therefore, we provide a 30-day guarantee. We will make every effort to ensure that you are completely satisfied with your purchase. Online shopping can seem daunting. We want you to know that there is absolutely zero risk of purchasing something. We won't make it difficult if you don't love it. We offer email and ticket support 24 hours a day, 7 days a week. If you require assistance, please contact us. Please contact customer service if you have any problems with your purchase.