Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Simple and easy to use

I am extremely pleased with the Miracle Balls. They are easy to use, require no special clothing or location and they really do work for relieving pain and stiffness. I ride a motorcycle and take long trips, sometimes riding 7 or 8 hours at a time. I take the balls with me and use them in the evening to eliminate tight, sore muscles.