The Geisha weighted Magentic Kegel Balls use a progressive weight system that can be used with or without the included silicone string to tone and strengthen the pelvic floor muscles. The core idea of the exercise is to start with one black ball on a silicone string and then gradually increase the weight by magnetizing 1 ball at a time. Geisha Magnetic Balls allows 7 levels of workout from 0.55 oz to 3 oz. (all 4 balls together). Geisha Magentic Kegel Balls are are for the body and made of 100% soft medical silicone.