Diane Twist Flex Rods are soft, flexible, and lightweight rollers used to create no heat curls in just a few minutes. Works for all lengths, textures and hair types. Rollers come in seven various diameters to create defined, loose, wavy, or bouncy curls with ease. Smaller diameter rods will result in tighter curls while larger diameter rods will create looser, more bouncy curls. Rods are made of a soft material and are comfortable enough to sleep in.