Functional elastic, which can be used in concealed waistbands (that is, the elastic is unseen, as it is sandwiched in the fabric, the white is undyed elastic and may have slight imperfections, marks etc, we do not class it has seconds as these imperfections in no way affect the functionality of the elastic and as it is designed to be concealed in the fabric will be unseen when used, and these imperfections come straight from the factory!