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 made in 50lb increments from 100lbs to 300lbs so that you can train your grip similar to training any other body part-- by increasing resistance. If you want to develop serious hand strength for a sport, or just want to impress your friends, than the Heavy Grips hand grippers is the perfect choice for you! The Heavy Grip 100 is perfect for beginners and warm-ups, and the Heavy Grip 300 takes a mind boggling 300lbs to close. Compare that to most store bought hand grippers that only take 50lbs of pressure to close! This is the perfect hand gripper for Arm Wrestlers, Powerlifters, Strongmen, Rock Climbers, Gymnasts and anyone else who wants to develop a strong crushing grip and massive wrists and forearms.