Flat 0.25 DD Curl Mix Tray 8-15mm have a slightly oval shape, rather than being rounded. The benefits of this shape is that the extensions have a much thicker look without adding weight. Flat lashes are a great option for those clients who are hoping for a dramatic look, but don't quite have the natural lashes to hold conventional extensions. Since the shape of the the flat lash is slightly oval, it hugs the natural lash resulting in improved retention.