As baby grows the Lifefactory 9 oz borosilicate glass baby bottle is the next step up. With a variety of nipple sizes and sippy caps the Life Factory bottle adapts to your baby's changing needs. The 9 oz. bottle comes with a silicone sleeve and a polypropylene flat cap. You'll appreciate the grippy surface of the colorful silicone sleeve, and you'll love the fact that you're using a glass bottle that is manufactured with high quality materials.