We Recommend Using The Peristaltic Nipple To Encourage Baby'S Natural Tongue Movement. The Ultra-Soft Silicone Rubber With Double Thickness Ensures Ideal Softness And Elasticity So Baby Can Latch On Easily And Comfortably. The Shape Fits Perfectly With Your Baby'S Tongue, Allowing Smooth Tongue Movement While Minimising Air Intake. The Nipple'S Roomy Base Helps Your Baby Open His Mouth Widely, Thereby Encouraging Steady Peristaltic Motion. The Streamlined Shape Makes It Easy For Mothers To Hold And Keep Clean. Made Of Premium Quality Borosillicate Glass Material With Excellent Transparency And High Heat Resistance Bpa Free