Full Thickening Mousse is powered by our patented Thickening Molecule, which uses tiny thickening dots to deliver BIG body. These mini miracle-workers create space between each strand, making thin, flat hair behave like naturally thick, full hair. Plus, a light hold keeps hair in place without the stiff finish. So you can make fullness look effortless. Full Thickening Mousse is for fine hair that needs hold, body and fullness.