The Haakaa Gen. 3 Glass Baby Bottle is designed to provide the most natural feeding experience possible for you and your baby. The orthodontic thumb-shaped teat mimics the shape of a mothers nipple during breastfeeding, and the offset position allows you to feed your baby without completely inverting the bottle. Our glass bottles are made from temperature-resistant borosilicate glass, making them safe to heat and freeze and perfect for storing expressed breast milk! The Gen. 3 Glass Bottle is ergonomically designed to be held easily and comfortably during feeding. Along with the anti-colic nipple included with this bottle, Haakaa Gen. 3 Glass Bottles are also compatible with the Gen. 3 Sippy Spout and Sealing Disk attachments. Please note: Always follow your countrys guidelines and recommendations to safely express and store breast milk.