They do not hold the cold for as long as I would have liked - so I strongly recommend ordering an extra sleeve
This product works!  What didn't work is that the instructions are printed on the sleeve that you freeze.  The label were not cut to fit the sleeve properly and I had to send 2 questions to the seller to explain how to freeze, etc.  The seller did answer promptly. They do not hold the cold for as long as I would have liked - so I strongly recommend ordering an extra sleeve.
Rating: 4 stars