The name speaks for itself! The flat rounded side is great for concealing under the eye, around the nose, or any other small area. It also works great as an eye shadow or lip brush. The flat straight side is perfect for crisp eyeliner. Both sides are made from synthetic bristles, making them hypoallergenic and vegan. They are designed to work well with both cream and powder cosmetics, picking up color well, and delivering a smooth application.