Haakaa wide neck glass bottles are made of borosilicate glass, A material that is resistant to shock temperatures.The unique shape allows the bottle to be held closer into the body therefore allowing dads to enjoy closeness with baby during feeding normally reserved for breastfeeding Mums.Product Features• Haakaa wide neck glass bottles are made of borosilicate glass, a material that is resistant to shock temperatures.• Anti-colic nipple allows baby to drink continuously without gasping for air or drinking bubbles• These wide neck glass bottles have an ergonomic design making them easy to hold, fill, and clean.• Compatible with the all Haakaa wide neck bottle accessories and breast pump.