• Two Replacement Silicone Nipples . • Level-1 Is Ideal For Feeding Newborns . • Exclusive For Dr. Brown’S Natural Flow Standard Baby Bottles . • Dishwasher Safe-Top Rack Only. • Made Of Super-Soft, High-Grade Silicone, Each Nipple Level Provides A Different Flow Rate. Compatible Exclusively With Dr. Brown’S Narrow-Neck Bottles.