Bra allows the wearer to use the tighter hooks as the bra stretches during its lifetime. Bras may be designed to enhance a woman's breast size, or to create cleavage, or for other aesthetic, fashion or more practical considerations. Nursing bras are designed to aid breast-feeding. Compression bras, such as sports bras, push against and minimize breast movement, whereas encapsulation bras have cups for support. Breast support may be built into some swimsuits, camisoles and dresses. Bras come in a variety of styles, including backless, balconette, convertible, shelf, full cup, demi-cup, minimizing, padded, plunge, posture, push-up, racerback, sheer, strapless, T-shirt, underwire,
Shelf life to the front of the shelf, so that most shoppers will pick them up first and thus they are likely to be sold before the end of their shelf life. Some stores can be fined for selling out of date products; most if not all would have to mark such products down as wasted, resulting in a financial loss. Shelf life depends on the degradation mechanism of the specific product. Most can be influenced by several factors: exposure to light, heat, moisture, transmission of gases, mechanical stresses, and contamination by things such as micro-organisms. Product quality is often mathematically modelled