This Nipple is our slowest-flow nipple, great for preemie and breastfed babies! Its uniquely designed Preemie Flow Nipple works together with our internal vent system to help babies feed at a pace that’s perfect for them. Each Preemie Flow nipple offers the same consistent flow, so both you and baby know exactly what to expect. Made of super-soft, high-grade silicone, these Preemie Flow Nipples fit all D best toys Standard/Narrow bottles. Dishwasher (top rack) and sterilizer safe. BPA free.