The ShakeSphere tumbler is simply the best!
Love that you can mash fruits in it before making a protein drink, it is definitely leak proof, that there is no mixing ball and easy to use and clean.
These are surprisingly effective, barely know how they work but I'll never use a 'ball' shaker again!
Really good does the job and keeps the drinks cold, only thing to get used to is slightly larger than the original and harder to shake one handed for smaller hands.
Excellent manufacturing! Better than my expectations!