With the GD Grip Pro adjustable gripper, you can start at the level of resistance that's right for you and increase the resistance as your grip strength improves. The resistance of the GD Grip Pro Grip is generated by COMPRESSING a solid steel spring. Other adjustable grippers create resistance by STRETCHING the spring, which can be dangerous. Stretching a spring places extreme tension on the components holding the spring in place. These components often fail, resulting in dangerous flying debris and metal shrapnel. Since there is no need to worry about the annoying squeak sound that most grippers make, you can use your gripper at work, on a plane, in a library, or even in a movie theater without bothering those around you. GD GRIP Pro : Adjustable 29~99 lb / Grip Strengthener Exerciser Wrist Strength Training.