A woman inserts the balls and will become aroused as they move while she moves or walks around. Also builds muscle strength.The balls are weighted so that you have to contract your muscles to hold them in. This is not only helpful with strengthening vaginal muscles but also helps strengthen bladder control. Use with intercourse or when doing your Kegel exercise routine. Although these Ben Wa balls are listed as vibrating they do not vibrate in a traditional way but through kinetic energy. 100% Stainless Steele Balls: Steel Balls, felt bag. Details two 100% Stainless Steel balls, 1 inch in diameter are designed to create intense stimulation when worn during Kegal exercising. Materials 100% Stainless Steel will not rust. Includes storage pouch. Includes 2 100% stainless steel balls.