* It contains a priming wax which is used to prep the brows for powder application. * Gives your brows definition by adding shape and body. * Shades and colours in sparse areas for a fuller brow look. The BYS Brow Definition Kit gives you the tools to prime your eyebrows, sculpt your eyebrows and create a perfect arch. Shape and shade your brows by filling in sparse areas and creating the illusion of full, thick, defined and natural looking eyebrows.