The Nuby Non-Drip Stage 1 Nipples with Vari-Flo valve allows the baby to control the liquid's flow rate. With your baby's comfort in mind, an anti-colic feature was designed into the nipple, helping to prevent ingestion of air by baby, which may colic. Also features teething nubs to help massage and stimulate the gums. Made of clear silicone and are BPA Free. 0 - 6 Months. 6 Pack, Standard Neck