The Evenflo Feeding Colostrum Collectors are specially designed for milk expression during the early stages of breastfeeding. Colostrum is produced by the body during the first few days after the baby is born, before your mature milk comes in. Rich in nutrients that help baby grow and build baby’s immune system, colostrum has a distinct yellow color, thick consistency and is made in smaller quantities. The Colostrum Collectors are ideally suited to your newborn’s stomach size and the smaller quantity of milk a newborn typically receives at each feeding. Due to the nature of colostrum, the normal smaller quantity and the thicker consistency, you may want to hand express the colostrum directly into these containers to maximize collection and reduce waste. To give baby the maximum nutrients of colostrum, it is recommended to feed freshly expressed colostrum. These colostrum collectors are compatible with the Balance + Standard Neck Nipple. As colostrum transitions to mature milk, these bottles can be used until your baby’s needs increase and volume is exceeded (typically around 3 weeks). The Colostrum Collectors are compatible with all Evenflo Feeding breast pumps and most other standard neck breast pump brands. The collectors are 100% free of BPA, polycarbonates, PVC and phthalates and are made of FDA-approved food grade material.