ADJUSTABLE: Hand Grip Strengthener is adjustable from 25kg to 90kg. With the this adjustable gripper, you can start at the level of resistance that's right for you and increase the resistance as your grip strength improves. To gain a good grip strength, you can do hand grip workout with a low resistance on a regular basis, while performing the Negatives or adding more intensity into your workouts and overload the muscle groups. DURABLE AND SAFE: The hand grip strengthener is crafted entirely from thermoplastic nylon and steel, even the adjustment wheel is solid steel. You can strengthen your hands every day for years. The resistance is generated by COMPRESSING a solid steel spring, not by STRETCHING the spring, which is more safe. EASY TO OPERATE: Adjust the resistance of the hand workout squeezer by twisting the gear. Twist to S side is to increase resistance. W side is to reduce the resistance of grip strength trainer. Please adjust to suitable resistance according to your training stage. NO NOISE and Portable: It is completely silent operation allows you to strengthen your grip anywhere without detection. Since there is no need to worry about the annoying squeak sound that most grippers make, you can use your hand grip strengthener at work, on a plane, in a library, or even in a movie theater without bothering those around you. Suitable for Most People: No matter you are a teenager, fitness enthusiast, athlete or even a woman. You can start your hands training step by step with adjustable grip strengtheners.