The main reason for skin sagging, wrinkles, and dullness is the loss of collagen in the dermis, which causes the "spring" of elastic fibers to break.
A large part of the reason why our skin is firm and elastic is that elastic fibers support it like a spring.
Collagen is an important nutritional factor for supplying elastic fibers, but the loss of collagen begins to accelerate after the age of 25 for most girls. If no nutrients can be supplied to elastic fibers, elastic fibers will break.
Radiofrequency can directly heat the dermis without heating the epidermis. When the dermis reaches a relatively high temperature, collagen will proliferate in large quantities, and elastic fibers will also shrink accordingly.
Collagen gradually fills up, elastic fibers slowly shrink and become elastic, and the skin is naturally plump and firm.