This product features a glass bottle with a plastic screw-on cap. Please ensure the cap is properly aligned and fully tightened before each use. This gift set does not include Premie or Size 1 slow-flow nipples. Please confirm the appropriate nipple flow for your baby before purchase. While designed to support a natural feeding experience, nipple acceptance varies by baby. This is a glass bottle. Avoid drops, impacts, or sudden temperature changes. When using a bottle warmer, follow instructions carefully and avoid prolonged overheating. Discontinue use immediately if any cracks or damage are observed. Philips Avent Natural glass bottles supporting your baby's natural drinking rhythm: baby controls the pace of the milk flow, just like breastfeeding Bottles are made of premium quality borosilicate glass, a BPA-free, heat and thermal shock resistant material; they can be safely stored in the fridge or warmed, they are easy to wash and sterilize Philips Avent glass baby bottles make it ea