Hi there. Excellent question.
Usage of Ben Wa balls creates a subtle stimulation, not meant to bring the user to immediate orgasm but rather to tease by rolling around in the vagina. It is possible to leave Ben Wa balls in one's vagina all day, or use them while seated in a rocking chair, for an effect that some find pleasurable. As long as your wife has a cervix, the balls can't get lost. Without a string to pull on, one simply removes them by inserting a finger into the vagina and finding the balls.
I don't know many women who are greatly turned on by these, since only the outer third of the vagina has much in the way of nerve endings. Like all toys, you can experiment with them and see if they bring pleasure. Dr. J
thank you doctor very much, your answer is very helpful for me and it disiped all my doubts
thanks