The boob glass bottle is the most innovative baby bottle on the market today. The new nipple design, clean flow vent system, 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 degree f/80 degree c. 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. Available in 5ounce and 8ounce sizes.