Stretch in suits helps them to spring back to form without affecting the feel of the fabric, or sacrificing comfort and mobility. Elastane,often called Spandex or Lycra, is a stretchy synthetic material. Full-on Lycra might cling to every contour on your body (think cycling gear), but combining it with other materials, like cotton, wool and polyester, will add just the right amount of give. You only need a small amount to get a close-fitting finish – even as little as 3%.