True about Spermicidal agents is all of the following, EXCEPT?

Spermicides function by : Providing a physical barrier to sperm penetration These have chemical spermicidal action i.e. nonionic surfactants that alter sperm surface membrane permeability, causing osmotic changes resulting in the killing of sperms The active ingredient is nonoxynol-9 or octoxynol-9. Improve the contraceptive effect of barrier methods like diaphragms, cervical caps, and condoms. No STD protection provided by these Spermicides must be deposited high in the vagina in contact with the cervix sholy before intercourse. Their duration of maximal effectiveness is usually no more than 1 hour, and thereafter, they must be reinseed before repeat intercourse. Douching is avoided for at least 6 hours after coitus.