Satisfyer Duo Balls - Set of 3Satisfyer Balls Duo is a set of kegel weights that contain weighted balls inside the body safe silicone design that vibrate with movement. This vibration activates the kegel muscles to flex and release, which can create more vaginal elasticity and even stronger orgasms. The set of 3 allow you to start at the lightest and work your way up to the heaviest most advanced ball as your kegels become stronger