Yany Metal Smart Balls.The first metal Kegel exerciser in the world..High quality Silicone wraps the luxurious metal balls, gives the user a better experience. The set comes with 2 sets of high quality aluminum balls in, 30gr (1.06 oz) balls in Gold color and 40gr (1.41 oz) balls in Blue color. Specifications: Ball material: Metal Belt material: Silicone Weight: Gold Ball 30gr/1.06oz, Blue ball 40gr/1.41oz Overall dimensions: Diameter: 31mm/1.21" Length: 155mm/6.10"