Support, style and beauty all in one. One, two and three layers of fabric strategically placed allow for support along with freedom of movement. Some prefer to use the bra for yoga and stretching, and others use the bra for higher impact activities like running and aerobics. As for sizing, for example, a 34B may prefer a small for running or playing sports to give the best support; but, during yoga or biking, a medium may give the best comfort/performance ratio. Think Nike brand sizing. Made of 70% viscose from bamboo, 25% organic cotton, and 5% spandex. Sizes: S, M, L, XL. Designed in California, made in China.