Lansinoh's glass baby bottle is specially designed for breastfed babies. It features our NaturalWave Nipple, which is clinically proven to reduce nipple confusion. This soft and flexible silicone nipple enables babies to engage in the same natural sucking actions learned at the breast, allowing for a smooth transition from breast to bottle and back again. The baby bottle glass is premium borosilicate so it's sturdy and shock-resistant. These baby feeding bottles are compatible with Lansinoh breast pumps for use as a breast pump bottle as long as they're supported. The NaturalWave nipple, collar, and cap are also compatible with Lansinoh plastic baby bottles. Use with any brand of breast milk storage bags or other form of breastmilk storage. Lansinoh Glass Bottles are more than a breast milk container, they're a way to help your baby get the best start in life!