Whether you're storing or traveling with bottles of milk, Dr. Brown's Silicone Baby Bottle Storage/Travel Caps keep your baby's meals safe. Designed to fit Dr. Brown's SIlicone bottles – simply remove the nipple and collar from the bottle, then screw on the cap to store milk. The storage/travel cap is leakproof and keeps breast milk, formula, and other liquids safe and fresh in the refrigerator, portable coolers, and even airplane carry-on bags. When flying, remove the nipple and collar from the bottle and replace with a travel/storage cap to help prevent leaks caused by cabin pressure changes. And when you're warming a bottle, seal with the storage/travel cap to help prevent leaks so you don't lose a drop. Fully reusable and dishwasher (top rack) and sterilizer safe. BPA free.