A contraceptive cap or diaphragm is a cup-like pregnancy preventive equipment made of thin, soft silicone and inserted into the vagina before sexual intercourse to cover the cervix and deter sperm from swimming from the vagina to the uterus to fertilize an egg   It has a 96% effective rate when used with a spermicide (A substance used for killing sperm), is hormone-free and comes in different sizes, and sometimes requires fitting by your doctor or health practitioner.