On the modern market two major barrier methods of contraception are available. These are cervical cap and diaphragm. The main task of these two and other similar devices is to prevent sperm from entering the uterus. If used together with some sort of spermicide these devices are very effective. The first device - cervical cap - is a cap of thimble shape which can be fitted over the cervix. Because the suction is present cervical cap is held in its place. The most usual material cervical caps are made of is latex just like the condoms but there are also cervical caps made of medical silicone. As long as the size and shape of the cervix varies from woman to woman doctor should find the right size for the user. The use of the device is pretty simple - it has to be inserted one hour before the actual sexual intercourse. And it can stay in the vagina for about eight hours or a little more. As it was mentioned before the effectiveness of cervical cap is not very high comparing to other methods of birth control - only about 80 - 90%. That is why most of doctors and cervical cap manufacturers recommend using it together with spermicide. And even more after vaginal birth the effectiveness of cervical cap can become even lower (only about 60%) because of the size changes. There was a slight decrease in popularity of this birth control method recently - possible because of the other more effective methods. Some women who have deeper vaginas may experience problem using cervical caps because it is much harder to insert it correctly. These women can use other barrier contraceptive mean - diaphragm. It is a small dome made of rubber. Its edges are O-ring moulded. It acts more or less like cervical cap with only difference it is very soft and flexible which makes insertion of the diaphragm much easier. And as cervical cap diaphragm has to be inserted about one hour or a little less before the sexual intercourse and removed 6-8 after it. The history of this contraceptive method is actually pretty interesting - some form of it was used in medieval times. Giacomo Casanova told in his memoirs that a lemon slice was used just like the diaphragm these days. And in addition lemon juice worked as a spermicide. As with cervical cap diaphragm has to be matched in size - so in most countries cervical cap and diaphragm are available by prescription. A visit to a doctor is needed to find just the right size of this contraceptive mean. Lately on the market you can find another kind of barrier contraceptive - it is called Lea's shield. The major difference of Lea's shield from previously mentioned means is that Lea's shield is a one-size-fits-all. Lea's shield is a reusable device made of silicon. Lea's shield usage is as easy as with other barrier devices. Due to special lea's shield features (like a valve for example) this device fits safely in its place and provides high effectiveness. Although the effectiveness of lea's shield is pretty high manufacturer of this device recommends using it together with nonoxynol-9 spermicide.