This 2-pack bundle includes Dr. Brown's Natural Flow Anti-Colic Options+ Narrow Glass Baby Bottles and Dr. Brown's Silicone Glass Bottle Sleeves to protect the bottles. The 4oz anti-colic bottles feature an internal vent system clinically proven to reduce colic by decreasing spit-up, burping and gas. The vacuum-free feeding experience closely mimics breastfeeding, with a slow flow Level 1 nipple designed for a more natural latch. The vent system also helps preserve nutrients and aids digestion. Made of thermal shock-resistant glass, the narrow bottles are safe for dishwasher, sterilizer and boiling water cleaning. The 100% silicone sleeves protect the eco-friendly glass bottles from breakage during use, cleaning and sterilizing. The stretchy yet durable mint green sleeves slide on easily over the 4oz bottles. A back window allows seeing measurements without removing the sleeve. The soft grip helps securely hold bottles during feedings. Both products are BPA-free and top rack dishwasher safe. With Dr. Brown's clinically proven anti-colic bottles and protective silicone sleeves, this bundle conveniently provides solutions to common feeding issues. The bottles aim to reduce feeding discomforts for babies while the sleeves prevent bottle damage. Together they offer a safe and smooth feeding experience for babies and parents.