Ben Wa balls have been around for centuries and originated in Japan. They were referred to as rin no tama (tinkling balls). The traditional Ben Wa balls are marble-sized metal balls that are not attached and float freely within the vagina. In order to extract the balls, the wearer must push them out with their Kegel muscles, jump up and down, sneeze or cough. These balls can also be worn during intercourse to stimulate both partners.
Many variations made of silicone or latex have recently become available. In these newer versions, the balls tend to be attached and may have a string that hangs down for removal much like a tampon. Sizes also vary from marble-sized to as large as an apricot. These larger balls are sometimes called Duotone balls.
Using Ben Wa balls for sexual stimulation generally does not lead to orgasm, but if worn for a longer period of time, the wearer can become aroused. Gynecologists and obstetricians often recommend these balls as a way to strengthen the pelvic floor muscles.