The Dr. Brown's Natural Flow Options+ Glass Baby Bottle Sleeve Bundle includes 9 oz and 5 oz wide-neck silicone sleeves that glow in the dark to protect Dr. Brown's glass baby bottles. The 100% silicone sleeves help prevent breakage of eco-friendly glass bottles during use, cleaning, and storage. Their grippy texture also makes bottles easy to hold when feeding baby. The 9 oz sleeve fits Dr. Brown's 9 oz glass bottles, while the 5 oz sleeve is made for 5 oz bottles. Both BPA-free sleeves feature a transparent back panel with volume markings so you can view measurements without removing the sleeve. Just expose the glow-in-the-dark silicone to light so it illuminates for late-night feeding visibility. The flexible sleeves withstand stretching and distortion from repeated use. Their tight fit helps limit glass contact if a bottle tips over. Sleeves can remain on bottles during cleaning for convenience - they are top-rack dishwasher safe, sterilizer safe, and boilable. To apply a sleeve, simply wet its interior and the bottle's exterior then slide into place. With protective silicone sleeves in two sizes, the bundle keeps Dr. Brown's glass bottles safe while in use and storage. The glow-in-the-dark feature also aids visibility for middle-of-the-night feedings.