Swing it or hit some tyres with it, the Ultimate Thor Hammer can improve your grip strength and make your forearms bigger. Some even claim that the hammer can grow your strength “to levels you didn't know was possible”. At sixteen pounds, the Ultimate Thor Hammer is bigger and heavier than the original Thor Hammer, but if that's not enough, the head can be loaded up to forty-five pounds for those who have superhuman strength. Like the original, its handle is oval instead of circle to improve gripping comfort. Try swingging two hammers at a time like this guy.