Closer to nature the most breast-like nipple ever. With anti-colic valve. 97% of moms recommended closer to nature to other moms. Flexes like breast nipple. Easy clean. Thicker flow. for a comfortable feed. Smooth silicone nipple feels closer to skin. Anti-colic valve to reduce air ingestion. For cereal thickened formula. Tommee Tippee closer to nature bottles are only suitable for use with Tommee Tippee closer to nature nipples.