Nanobébé's Silicone Baby Bottle Nipples are soft as skin for an easy transition from breast feeding to bottle. Gen 2 nipples for our newly updated Breastmilk Bottles (clear one-piece base) and Sets! Gen 1 nipples are still available for the original Breastmilk Bottles (white two-piece base). Both versions will work with the Flexy Silicone Bottle.