Philips AVENT bottles have been clinically proven* to reduce the risk of colic in infants & decrease irritability in babies especially at night. PLUS POINTS: Resistant to shock & heat, these bottles have anti-colic adapter rings to help prevent leakage. Wide bottle base provides extra stability. Set also comes with flexible, variable flow teats (suitable from 3 months), ideal for good appetites & thicker liquids. Exclusive skirt: more comfortable for your baby, the liquid flows at a rhythm controlled by them.WHAT YOU NEED TO KNOW: In polypropylene, guaranteed BPA-free.2-year warranty. Always check temperature before giving baby the bottle. * Tests found that babies fed from a Philips AVENT bottle experienced less colic & were less irritable than those fed from a conventional bottle.