This barrier method is a soft, disk-shaped device with a loop for taking it out. It is made out of polyurethane foam and contains the spermicide nonoxynol-9. Spermicide kills sperm.
Before having sex, you wet the sponge and place it, loop side down, inside your vagina to cover the cervix. The sponge is effective for more than one act of intercourse for up to 24 hours. It needs to be left in for at least 6 hours after having sex to prevent pregnancy. It must then be taken out within 30 hours after it is inserted.
Only one kind of contraceptive sponge is sold in the U.S.. It is called the Today® Sponge. Women who are sensitive to the spermicide nonoxynol-9 should not use the sponge.
Reference: U.S. Department of Health and Human Services