While the size of the balls maybe intimidating, compared to the smaller average size BenWa Balls, the high quality silicone and refined design of the Smartballs make for a lot of fun. With a little jell, some patience and practice, you may even forget you’ve inserted the Smartballs until you move around. As you move, the smaller heavy metal ball inside bounces around, creating erotic tingling vibrations. The strength of the vibrations varies with each movement so experimenting with this toy will never be dull. The Smartballs are an excellent choice for vaginal stimulation and muscle strengthening, all the while reminding you of your sensual womanliness. This is a must have toy, even if you are the only one that knows you’re using them . . . even now ;)