Super-sensitive valve Soft Natural feel silicone Teat. Easy hold bottle with a slow flow teat BPA-free for total reassurance. Designed in conjunction with breastfeeding experts, the Tommee Tippee Closer to Nature easi-vent teat mimics the natural flex, movement and softness of a mum's breast, to make switching between breast and bottle easier than ever before. The Closer to Nature 260ml bottles have been designed for smaller expressed breast milk feeds. They also have an anti-colic valve which you can actually see working. Every bottle is BPA free.