VACUUM INSULATED: Keeps liquids cold for up to 12 hours (iced) SAFE: Only 100% plastic-free bottles on the market; only Made Safe® Certified bottles on the planet Baby Grows... Bottle Evolves™: This bottle easily converts into a sippy bottle, straw bottle or sport/water bottle by simply swapping the nipple out for another Pura silicone lid Zero Plastic... Zero Yuck™: Bottle and collar crafted from safe, anti-bacterial, #304 stainless steel and Pura Anti-Colic Natural Vent Nipple™ crafted from 100% medical grade silicone BPA-free, BPS-free, PP-free, Polypropylene-free, phthalate-free and will not leach toxins like plastic bottles and lids because our products do not contain any plastic! Internal volume markings make measuring your child's milk or other beverage a snap. Each ounce is marked and can be seen by glancing inside the bottle. Compatible with wide neck nipples from Pura, ThinkBaby™, BornFree™ and many others 100% medical grade silicone bottle sleeve nipple cover Hand wash recommended