Underwire bras are probably the most popular style of bra on the market. They provide lift, shaping and support and are especially useful for woman who wear C cups or larger. Made of flexible wire or plastic or plastic-coated metal, the underwire is sewn into layers of fabric under the bra cups. Underwires also provide breast separation for a shapely silhouette.
Underwire bras come in virtually every style including demi-cup bras. A demi bras has a contoured cup with the upper portion cut away to expose the top of the breasts. Demi cup underwire bras often have wide-set shoulder straps as well. While not offering as much support or coverage as full-cup bras, an underwire demi-cup bra is ideal under clothing with low necklines. It's also an attractive and sexy style.