Wikipedia
FemCap is a cervical barrier contraceptive. As of February 2009, FemCap is the only brand of cervical cap available in the United States.
FemCap is made of silicone, its shape is similar to a sailor's hat. FemCap has had two designs; the newer design added a loop, molded into the silicone, to assist with removal of the device. Only the newer design is available. There are three sizes of FemCap: 22, 26, and 30 mm. The smallest rim diameter (22mm) is intended for women who have never been pregnant. The medium (26mm) cap is intended for women who have been pregnant but have not had a vaginal delivery. The largest (30mm) is intended for women who have had a vaginal delivery of a full-term baby. The only exception to this rule, if a woman had a spontaneous miscarriage and/or she was not aware of it, in which case she should receive the 26mm FemCap. If the woman and her doctor are in doubt it is more appropriate to use the 26mm FemCap.
The new version of the Femcap performed poorly in a user acceptability study, suggesting that the modifications to the FemCap significantly increased coital pain or discomfort among female users and their male sex partners, and that the modifications did not improve ease of use overall. However, FemCap users are still less likely to report such pain or discomfort than diaphragm users.