Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Saved My Arm

I switched from a regular old mouse to an older version of this product several years ago. The older model helped with the arm pain I was having, but I hated it because the little plastic pieces that held the little red beads that the ball glides on broke very easily, and then it was pretty difficult to move the ball. I switched to this version at work when it came out and I love it! The construction is much sturdier. The ball is much easier to move. While a lot of people seem to have angle problems, I find it's very comfortable to rest the heel of my hand on the wrist rest and use the ball, scroll ring and buttons. I bought one for home use, too, and plan to never go back to a regular mouse. It really did save my hand and arm, the pain was very bad pre-Kensington Expert Mouse Optical USB Trackball. Now I can work for hours with no negative effect.