The cervical cap is a thimble-shaped latex barrier that fits over the cervix and uses suction to block sperm from entering the uterus. It is 84-91% effective for women who have never given birth and 68-74% effective for women who have. The cap costs around $70 plus fitting fees from a doctor, who determines the proper size and shows insertion. It can be inserted in advance of sex and is comfortable, but requires fitting and may be difficult to use correctly.