The Supplemental Nursing System (SNS) is a lactation aid that consists of a container filled with supplementary milk that is clipped securely to a bra strap, shirt or pillow. While the baby is latched at the breast / chest, a thin, flexible tube is placed alongside the nipple into the baby's mouth and a controlled and consistent flow of milk is released as they feed. It's often used when a baby may have difficulty latching, has a weak suck, or needs additional nourishment beyond what the mother's breast milk alone can provide.