HAND and FINGER EXERCISER - Perfect for musicians and sports enthusiasts. It will improve dexterity and performance. Best for treatment of patients with hand injuries, tendonitis, arthritis, carpal tunnel, tennis elbow. Accelerates blood circulation. ADJUSTABLE DESIGN - Easy to change and allows a wide variety and range of exercises for a wide range of age groups and fitness levels by screwing or unscrewing the knob to adjust spring tension from 22lbs/10kg to 88lbs/40kg.