Unusual Cup / Product For A Special Cup

It's a special kind of cup which can roll and be waterproof.It is made by a special material, soft-plastic.
The cup is easy to carry and the "cup" exsits as a belt when it is not in use.
It is so light that we can put it in the bag, nip it in the book and so on; when we need drink water, we should just line the edge of their mutual co-deduction, then you can get a close beautiful cup.
This product used mainly in outdoor activities such as travel and family time.Easy drinking and easy cleaning and also environmental.