The Boob Glass Bottle with Silicone Sleeve is the most innovative baby bottle on the market today. The nipple design, CleanFlow Vent System, silicone sleeve, and bottle are state-of-the-art and use today's best design and materials. Some old fashioned things just can't be improved upon and the Boob Glass Bottle is a classic example. Glass does not absorb odor, color or taste, so it is an excellent material for baby bottles. The Boob Glass Bottle can withstand a sudden temperature change of 176-degrees Fahrenheit/80-degrees Celsius. The silicone sleeve reduces slips and provides an excellent cushion against bumps and drops. Transitioning from breast-to-bottle, bottle-to-breast, or bottle-to-bottle can be frustrating and delicate, but the Boob Bottle's innovation and technology make it a "natural" choice for quick and easy transitions.