Double vaginal balls, also known as Kegel balls, contain rotating metal balls that stimulate and strengthen the pelvic floor muscles. They consist of two balls inserted into the vagina to trigger automatic pelvic floor muscle contractions and improve muscle tone. Bi-Balls are ideal for safe, easy training, and the double-ball design is suitable for those who have already started training and are ready to take the next step. These Kegel balls are also an excellent aid in preventing urinary incontinence.