The Heavy Grips? hand gripper series was developed for athletes who want to take the training of their grip strength to the next level. These high quality aluminum-handled handgrippers are crafted with 50 inch-force-lb torque increments from 100lbs to 350lbs so that you can train your grip similar to training any other bodypart-- by increasing resistance. This will finally allow you to build the huge forearms and crushing grip you have been unable to achieve by doing endless reps with plastic-handled hand-grippers.If you want to develop serious hand strength for a sport or just want to impress your friends than the Heavy Grips? hand grippers are the perfect choice for you! If you're worried about working hard getting sore hands and possibly some calluses on your fingers than this product is not for you!