Each Level 1 Nipple offers the same consistent flow, so both you and baby know exactly what to expect. Made of super-soft, high-grade silicone, the Level 1 Nipple fits all Dr. Brown?s Standard/Narrow Bottles. The suggested age range for the Level 1 nipple is 0 months+ but baby?s preferred flow rate may vary. Dishwasher (top rack) and sterilizer safe nipple. BPA free.