Exclusively use of new reinforced ABS and heat-treated spring with high strength which is made of fine steel. Much more durable in use than similar products on the market. You can adjust the strength tension from 10kg to 40kg by turning the red rotary knob. An excellent training tool that strengthens your hands, wrist and forearm. TPR handle, good elasticity, anti-slippery design. Small, exquisite, lightweight and portable, you can carry it with you to exercise anytime. Suitable for the elderly, the office crowd and sports enthusiasts.