The inside of the cup is made of 100% silk, and the back is made of a stretchy, sweat-absorbing, quick-drying material, for a comfortable feel against the skin. It gently supports the bust, which tends to flow sideways, and also helps prevent night sweats. It is a pull-over type, so the back is flat and the under-elastic is only on the back, so it doesn't feel tight. The elegant design will make you feel glamorous 24 hours a day.