Milliard Hand Grip Strengthener; Forearm Exerciser and Increases Hand Dexterity- Great for Wrist and Finger Therapy (2 Pack) Don't neglect your hand muscles. Effective gripping leads to effective lifting! Strengthen your forearms and improve your hand dexterity. Great for relieving stress and tension as you squeeze away bad vibes. Portable and easy to use at home on the couch, at work from your desk, or at the gym on the bench. Product Size: Spring 4.5mm