Bottles that are Leak-Proof, Airtight and Convenient The cap closes tightly and firmly making the set of bottles completely leak-proof and airtight. With this design, the water stored in these bottles will remain clean and potable for a longer period of time if placed in a cool place. The high quality plastic makes the set unbreakable and safe for use. The clear body of the bottles also make it easy to identify the liquid inside the bottle. Stay Hydrated All Day Long This bottle set by Cello is ideal for staying hydrated all throughout the day. Whether it is at work or a day at school or a road trip, these reusable and vibrant bottles can hold 1 litre of liquid, making it super convenient for use.