Thinx are washable, reusable period underwear. They look, feel, and fit like normal underwear. Contrast trim gives these bikinis a touch of athleisurewear. With their built-in protection and absorbency, you never have to worry about accidents. Thinx moderate absorbency cotton bikinis can hold up to three regular tampons' worth. The waistband sits at the low hip, and it has full back coverage and narrow sides.