Nova exercise balls are an expertly designed set of three different exercise balls to perform kegel ball exercises with. Each ball is equipped with a silicone string to easily take out the ball after use. The entire Nova ball is made of body-safe silicone which is 100% waterproof. According to the kegel exercis e theory, we designed these kegel exercise courses especially to help those who want to tighten their vagina mucles after giving birth. The set of Nova balls have three gradual increased weights for different exercise needs. Effective kegel exercise helps to strengthen a woman’ s PC muscle (pubococcygeus muscle), improving vaginal health while bringing sexual benefits and satisfaction. For daily exercise or postpartum recovery, Nova exercise balls are the perfect choice for your PC muscle strengthening needs. Product Features ● Fully-covered with soft silicone ● Fully submergible 100% waterproof ● Three different weights ● Silicone string for easy removal ● Environmentally friendly material Specifications ● Material: Body-safe silicone ● Single Ball Dimension: Φ36X135 mm ● Double Ball Dimension: Φ32X170 mm ● Double Ball Dimension: Φ28X162 mm ● Weight: 49g, 75g, 95g ● Water Repellency: 100% waterproof