From breast to bottle and back again : Soft and flexible teats allow baby to control the milk flow and maintain establishing breastfeeding patterns. NaturalWave baby bottle teats : Clinically proven to reduce nipple confusion and features a wide textured base for easy-latch on. Anti colic baby bottles : Innovative Air Ventilation System (AVS) reduces intake of air, a potential cause of colic & spit up. NEW: Each baby bottle comes with a medium flow teat and a stackable lid for space-saving milk storage. Also handy for storing snacks from 6+ months. Efficiency : Effortlessly connects to all Lansinoh breast pumps to pump directly into our baby bottles & milk storage bags.