The G-Vibe Gballs 2 is your personal coach for kegel exercise. Use the App to access a personalized virtual coach, 6 comprehensive training courses, a voice guide, daily target, and a fun badge and reward system. Can also be used to track daily exercise activity. Gballs have a ultra sensitive pressure sensor that ensure accuracy of biofeedback and use Bluetooth 4.0 technology. Gballs also work in non-app mode and are splash proof. From Fun Toys.