Ergonomic design fits a wide range of hand sizes, making it suitable for men, women, seniors, and teenagers. 42 mm diameter round hand trainer with a clear scale and auto zero for accurate, repeatable readings. Designed for athletes and sports enthusiasts who want to increase hand, wrist, forearm, and finger strength for climbing, shooting, bodybuilding, golf, tennis, and more. Wide tension range provides versatile training and supports users with arthritis, rheumatoid arthritis, tendonitis, carpal tunnel, tennis elbow, and recovery from broken wrist or tendon surgery. Use scenarios - Rock climbing grip training to improve hold strength and endurance. - Golf and tennis practice to enhance swing power and control through stronger forearms and fingers. - Rehabilitation and daily functional strength during recovery from wrist or tendon injuries.