Sunday Riley CEO 15% Vitamin C Brightening Serum Brand new 5 ml size uses a sophisticated, ultra-powerful form of Vitamin C called THD Ascorbate. Both highly stable and oil-soluble, THD Ascorbate rapidly absorbs into the skin for visible anti-aging benefits, including visual improvement in loss of firmness, the appearance of lines and wrinkles, and dark spots and dullness. #sephora #serum #sundayriley #makeup #skincare