Norelgestromin/ethinyl estradiol patch is an estrogen/progestin combination. It works by preventing ovulation. It may also change cervical mucus to prevent the sperm from reaching the egg and change the lining of the uterus to prevent a fertilized egg from implanting in the uterus. More info please see: http://www.oemcondoms.com/e_productshow/?32-ethinyl-estradiol-patch-32.html