Duo balls in a seamless silicone coating. Inside their silicone skin the metal balls can freely flow, which provides a natural massage with each body movement. The weight of the rolling Duo Balls is 90 gr, which helps train and strengthen the pelvic muscles. When inserting the In Bloom Duo Balls in the vagina, make sure that at least 2 cm of the string keeps out. That way pulling the set out is easy.