It’s all about the geometry. By spreading the milk into a thin layer across the bottle's concave surface, breast milk is able to both cool and warm 2-3 times faster than in standard bottles.Quick Cooling: The longer breast milk is left out at room temperature, the more bacteria continues to grow, reducing its nutritional value. It is beneficial to cool breast milk as quickly as possible so that the immunological properties inside go towards baby’s nutrition rather than to fighting bacterial growth. Quick and Even Warming: The popular method of using boiling water to warm breast milk is not recommended by health professionals and the World Health Organization because of the likelihood of overheating the milk. This damages nutrients and increases the risk of hot spots. As a live biological fluid, breast milk begins to deteriorate above body temperature, so it is recommended to warm it gently using warm tap water. Nanobébé’s Breastmilk Bottle allows for quick and even warming at safe temperatures.