Well worth the money!
My son had arm surgery and needs a cast for 6 weeks.  Plastic bags were not cutting it.  After reading reviews I gave this a shot.  Really does the job.  Getting the seal over the top part of the arm was a bit difficult as the cast is larger there, and he is still tender.  Aside from that, I couldnt design a better product for this purpose.  He is 10, and I opted for the 11-13 size.  I'm glad I did because it is a perfect fit!
Rating: 5 stars