Optimal nipple shape and lenth for a perfect latch With minimal pieces, cleaning and assembly are a snap Includes 3 shells, 3 nipples, 3 collars, 3 silicone pouches, and 3 caps 4oz Bottles Include Stage 1 Nipples - Slow flow Made without BPA or PVC The revolutionary air-free feeding design of our NURSH™ Silicone Pouch Bottle feature a 100% silicone pouch that collapses as your little one drinks, squeezing out the nasty gas-inducing air that causes colic. No straws, vents or valves here-so it's a snap to clean and assemble. The silicone can even be boiled, sterilized, microwaved, and frozen. Silicone pouches are reusable.