These hair rollers are the perfect choice for those looking for a looser, more relaxed curl. And their soft foam material means you can wear them comfortably for hours, even overnight! Flex Grip Rods have ends that lock together, allowing you to wind them into tighter curls. Soft Twist Rods are open-ended, leaving the tightness and definition of the curls up to how tightly you wrap your hair around each rod.