iHuniu Power Twister Bar Chest Resistance Arm Builder for Strengthening Weight Training (20kg to 100kg Options) MULTI CHOICE: 20kg, 30kg, 40kg, 50kg, 60kg, 80kg,100kg levels for you choose. iHuniu Original Brand. MATERIALS: Quality carbon high grade steel springs and non-slip molded plastic handle. PRECAUTIONS: Please make sure you have enough power to use the 50kg or more levels. MAX SPRINGS POWER: 100 KG/220 LB to challenge yourself. please wear the hand strap before training. WORKOUT ANYWHERE: Perfect for building upper body strength, strengthen your arm muscle builder. Enhance Your Forearm and Wrist Strength. Increase Chest Muscles. Hold Your Breath to Bend it, Than Can Increase Lung Capacity. Increased Grip Strength. Effectively Prevent Your Grip Strength From Decreasing, Prevent from the Mouse Hand Pain. Enhance Your Back, Shoulders and Biceps Strength. Prevention From Periarthritis of Shoulder ABS Engineering Plastic, Slip Resistant Design. High-Quality Carbon Steel to Prevent Deformation, Internal and External Double Spring Design. The High-Density Braided Safety Wristband Effectively Prevents Breakage.