Whether you're storing in the refrigerator or stowing for travel, the Dr. Brown's - Storage Travel Cap gets your baby bottle ready for anything! Take the Storage Travel Cap along with your bottle wherever it goes to keep the contents safe and secure. Simply remove the nipple, collar, and internal vent system, screw on the Storage Travel Cap, and you're done! Seal the bottle when you're finished pumping, when transporting, and even when warming the bottle. It's also the perfect companion when you're traveling by air, preventing the effects of a pressurized cabin on the Dr. Brown's vacuum-free bottle. Available in Narrow/Standard and Wide-Neck. BPA free.