The Lansinoh Natural Wave Flow Teats x 2 - Medium includes two super soft and flexible 100% silicone, fast flow teats. The Lansinoh teats are designed for easy latch on and effective suction which encourages baby's wave-like tongue movement, promoting instinctive sucking action for natural oral development . The AVSTM Air Ventilation System reduces intake of air, which is a potential cause of colic enabling your baby to feed comfortably. These Lansinoh teats are clinically proven to help maintain established breastfeeding patterns.