NUK Nature Sense is designed to create a drinking sensation similar to that of breastfeeding. The NUK Nature Sense Teat is modeled on a mother's nipple - with several tiny openings just like the milk ducts in a mother's breast for an even flow. The shape of the teat is also designed to resemble the female nipple when breastfeeding for it adapts flexibly to the tongue and palate when the baby feeds. The material used is soft, and is ideal for breastfed babies that will take an occasional bottle or for when it is time to wean. The Nature Sense Teat is available with three different drinking holes (S, M, and L). M & L are Sold separately. Depending on baby's individual sucking strength, these different hole variants allow for an optimal drinking flow. Small is a slow flow ideal for breast milk, Medium is a regular flow and Large is a fast flow. The NUK Nature Sense Baby Bottles now come with the added benefit of a Temperature Control indicator. This indicator is located on the scale on the bottle and changes colour depending on the temperature of the contents. If too hot, the normally blue indicator turns white.