This #5 Serum has become my favorite for skin brightening and texture, and to protect from the elements. It produces an immediate glowy and refined look that wears perfectly under any other skincare and makeup products without pilling. I combine this with the Numbuzin #5 brightening toner pads a few times per week, but use this serum every morning. It is also very soothing, unlike some other Vitamin C serums that can cause irritation. The multiple ingredients in this product make it highly more effective, including Arbutin, TXA, panthenol and bifida. EXCELLENT!