David Horne's Vulcan Hand Gripper
The design of this gripper is different from the rest of this list, developed by competitive arm wrestler, strongman, and one of the revolutionaries in the world of grip strength – this is the most versatile and valuable grip strength tool available.
The Vulcan has more levels of tension than you will ever need, regardless of your current level of strength or your grip strength aspirations, you will never outgrow this piece of equipment. The Vulcan is a rock solid piece of equipment that after hundreds of uses still operates as well as it did upon its arrival. You will pay a little more for the Vulcan than you will for another a good torsion gripper, but with the construction and the massive adjustability it is worth every penny.