Philips Avent SCF425/27 Anti-colic baby bottle Variable Flow Nipple lets babies control the flow of milk like with breastfeeding, which can reduce spit-up and overeating. Philips Avent's anti-colic valve flexes to keep air in the bottle and out of your baby's tummy, a feature that reduces fussing and colic. In a clinical trial, two-week-old infants fed with a Philips Avent Anti-colic baby bottle experienced less colic than babies fed with a conventional bottle, with the greatest difference seen at night. Designed for babies at least 3 months old, the slot hole design allows you to change the flow of milk, provides an extra fast flow and accommodates thicker liquids. Simply turn the bottle to line up the I, II or III marking with your baby's nose to choose between slow, medium and fast flow. The nipple is made of flavorless, odorless silicone that resists discoloring and stickiness. The nipple's soft, rounded shape promotes feeding for babies who nurse from both the breast and a bottle. The Anti-colic baby bottle BPA Free nipples are dishwasher safe and can be sterilized by boiling for five minutes or by using a Philips Avent steam sterilizer.