The Avent Pack Natural Response Crystal 0-6Months Scd878/11 is a set of bottles designed for babies from 0-6 months. These bottles are made of glass and have a natural flow nipple that mimics the shape of a mother's breast. To use this product, simply wash and sterilise the bottles before use. Then fill the bottle with breastmilk or formula and attach the nipple. Make sure the nipple is tight to prevent leakage and feed baby by holding the bottle at a proper angle.