The Dr. Brown's baby bottle nipple bundle includes two complementary sets of silicone nipples. The first set of 6 Y-Cut nipples is designed for thicker liquids when baby is ready to transition from breast milk or formula. Its shape encourages proper latching and the Anti-Colic internal vent system reduces colic symptoms. The second set of 6 Level 4 fast flow nipples is designed for 9+ month old babies that need a higher flow rate. Its breast-like shape also encourages proper latching while the Anti-Colic system decreases gas. Both 100% silicone nipple sets fit Dr. Brown's narrow baby bottles and provide a consistent flow rate closest to breastfeeding so baby can feed at their own pace. Their nutrient preserving and digestion boosting vent system enables comfortable feedings and better sleep. With stages for thicker liquids and faster flow, this nipple bundle covers multiple feeding needs as baby grows from breast milk to formula and cereal. Dishwasher safe and BPA free, these complementary nipple sets support both baby's health and mom's convenience.