It has a thimble shape and fits snugly over the cervix; suction is used to keep the cap in place, like the Prentif or by surface viscosity like the Oves pictured at right. The inside of the cap may be filled with a spermicide to combat sperm which get past the cap. There are caps in different styles and sizes. They are made of latex or medical silicone.

Initially a health care provider should find the right size for the user. The cap is inserted prior to sexual intercourse and should remain in the vagina for six to eight hours.

The cervical cap is 85-98% effective at preventing pregnancy for women who have never given birth vaginally; effectiveness drops to 80-95% after vaginal birth due to shape changes of the cervix and vaginal canal.

The cap-like device Lea's shield (Canada Brand, in US: Lea Contraceptive, in Europe: LEA contraceptivum) needs no fitting. It stays in place because of suction.

A number of cervical cap makers have discontinued sales in the US, most notably the makers of the Prentif Cavity-Rim Cervical Cap. While other caps have come onto the market (the Oves Cap, the Lea cap, as well as the FemCap).