The Avent Pack Natural Response Bottles SCD837/12 is a set of bottles designed to feed babies naturally. To use this product, you must first sterilise the bottles and teats. Then you can fill the bottle with breast milk or formula and attach the teat. Make sure the nipple is tight to prevent leakage. Finally, you can feed the baby by holding the bottle upright and allowing the baby to suck at his or her own pace.