The main property of hyaluronic acid is its high capacity for retaining water. It can hold up nearly one thousand times its own molecular weight in water. This property makes hyaluronic acid one of the most important elements for long-lasting skin hydration. Hyaluronic acid fillers are injected into a subcutaneous layer of the skin, to correct wrinkles and lines, fill-in hollows as well as shape the lip and facial contours. Fillers are also used to restore elasticity and moisture to the skin, as well as reduce some skin surface irregularities.