A condom (// or UK //) is a barrier device commonly used during sexual intercourse to reduce the probability of pregnancy and spreading sexually transmitted diseases. It is put on a man's erect penis and physically blocks ejaculated semen from entering the body of a sexual partner. Condoms are also used for collection of semen for use in infertility treatment. Because condoms are waterproof, elastic, and durable, they are also used for non-sexual purposes such as creating waterproof microphones and protecting rifle barrels from clogging. In the modern age, condoms are most often made from latex, but some are made from other materials such as polyurethane, polyisoprene, or lamb intestine. A female condom is also available, often made of nitrile.