Nicka K Tighten Collagen Ampoule Serum is a skincare product that is specially formulated to deliver high concentrations of ingredients targeting specific areas of concern. They are often gel-based, clear or liquid and tend to be less thicker than moisturizer. When serum is added into your skincare regime, it works with your moisturizer and other skincare products to meet your skin care needs. Continue to use moisturizer as this creates a top barrier on skin to lock in all that good stuff.