The philips avent classic bottles have been clinically proven to reduce colic in babies the anti colic system is integrated into the teat so you can assemble and clean the bottle with ease this system involves a unique skirt on the teat to flex which allows air into the bottle and prevents a vacuum build up this classic bottle has a unique ergonomic shape to keep it easy to hold in any direction for maximum comfort including your babys tiny hands the bottle also only has four parts for q