Natural Feeling Is The Pure Borosilicate Glass Baby Bottle. It Is Hygienic And Safe: It Resists Thermal Changes And High Temperatures, And Maintains Its Properties Unaltered Over Time. The Double Anti-Colic Valve Guarantees Maximum Protection From Colic. In Addition, The Tattersall Always Remains Full Of Milk To Prevent Air Ingestion. The Special Silicone "Mother Effect", The Softness And Flexibility Of The Teat Help To Reproduce Natural Sucking And Facilitate The Alternation Between Breast And Bottle.