The soft silicone sippy spout is used in place of the nipple on the Dr. Brown's bottle that's already familiar to baby. Easy grip 100% flexible silicone handles are removable and fit most narrow bottles, while the snap-on cap keeps the spout clean when on-the-go. The sippy spout fits any Dr. Brown's Options+(TM) Narrow bottle after the internal vent is removed. All parts are safe for use in dishwasher (top rack only), electric and microwave sterilizers or boiling water. Easy to grip, easy to sip! Dr. Brown's Milestones(TM) Narrow Sippy Bottle with silicone handles is the perfect first step for baby's transition from bottle to cup.