These silicone ben wa balls have a smooth finishing for non-stop erotic movement. They are covered in a silky soft medical grade which enjoyment is assured with your loved one or for solo fun. Easy to use. Insert and rock for the orgasm of your life. The finished balls do not vibrate in the conventional way but rather by the natural kinetic energy created by your movement. Any movement you make will send shock waves of pure delight coursing through your body.