Revolutionary Teat Revolutionary teat developed with breastfeeding experts and Mums to mimic the breast's natural flex, stretch and movement Super Sensitive Easi-Vent valve Nipples are available in Slow, Medium, Fast & Vari-Flow rates Soft Silicone Teat The soft silicone teat feels like skin, and gently elongates and flexes during feeding to mimic natural breastfeeding action. Breast like Shape The breast like larger shaped teat of the Closer to Nature bottle allows baby to latch on easily and further supports the transition between bottle and breast. Baby Safe All the Tommee Tippee Closer to Nature teats are BPA-free for total reassurance