The Fun Factory Smartballs playfully get your pelvic muscles in shape. The velvety and sleek Smartballs Teneo Duo goes the dual ball route, sure to captivate lovers of vaginal balls and convert newbies. The ridges on the balls add sensation, while the inner balls rotate quietly in response to movement, making kegel exercises fun and stimulating. The ergonomically-formed finger hollow on the base makes insertion easy, while the silicone removal loop allows for effortless removal. 4" insertable, 1 1/2" in diameter.