I've been using Gravity Gripp balls for about five years, and I love them. The pound of weight feels nice in my hand, and the squeezing is good for my hands and forearms. I get some exercise value from squeezing, but much of what I get is stress relief. Everyone at work laughs about me and my "squeezy balls," but they make me happy. My local sporting goods store stopped carrying the a few years ago, and finding them on Amazon has been great.Folks who've never used them might want a couple of warnings. First, they don't last forever. Depending on your strength, how much you squeeze them, and how dirty your hands are, the rubber covers break down. My co-workers can gauge my stress levels by how quickly I have to change these balls. Eventually, they lose some of the resistance, so you aren't working your muscles as hard. Later, they break down to the point of developing a hole. They are filled with small lead shot and some seeds. The seeds tend to be ground to dust with use. The hole will allow the shot to escape, and I've given a squeeze and then had lead shot all over my desk. If you make the mistake of putting one in the back of the desk instead of throwing it away immediately, the cover breaks down into a gooey material.None of these disadvantages lessens my love for the Gravity Gripp. If you want a nice hand strengthener and stress reliever, you need to try one of these.