Duotone Orgasm Balls smooth plastic balls are weighted for vaginal exercise. String attachment for retrieval. Ben Wa style balls. Multiple use scientifically weighted balls can be used in conjunction with Kegel exercises. Balls do not vibrate with batteries but rather with kinetic energy. Use for pelvic exercise by holding them in to strengthen muscles. Safe and pure for body and pleasure. Made using phthalate free, non-toxic materials Balls ABS plastic, nylon cord. Each ball measures 1.25 inches in diameter.