AVENT NIPPEL CLASSIC 1M+ , AVENT nipple anti-colic valve flexes to keep air in the bottle and out of your baby's tummy, a feature that reduces fussing and colic. two-week-old infants fed with a AVENT Classic bottle experienced less colic than babies fed with a conventional bottle, with the greatest difference seen at night. Appropriate for babies at least 1 month old, these dual-hole nipples offer a slow 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 Classic BPA Free nipples are dishwasher safe and can be sterilized by boiling for five minutes or by using steam sterilizer.