Features： 1、Improved grip strength, reduced stiffness and pain, increase strength in the fingers, hands, wrists and forearms, while reducing stiffness and joint pain by stimulating blood circulation in the forearm and hand. 2、Grip ball provides grip training for office workers and students, as well as those in need of arthritis, rehabilitation exercises. 3、Consists of a yellow super soft ball, an orange soft ball, a red soft ball, a blue hard ball, and a green super hard ball. 4、Each resistance level can be used in interval training. size, a comfortable size for an adult hand with an outside diameter of 5cm / 2in. 5、Durable anti?skid external grip treatment ball is made of a high?quality composite material, odorless and latex free. Specification： Item Type: Hand Exercise Ball Material: Silicone Color and Hardness: Green 35 degrees, blue 30 degrees, orange 20 degrees, red 25 degrees, yellow 15 degrees Exercise to build up knuckles and palm muscles Pressure finger, loosening joint Exercise your fingers and arm strength. The size of the grip ball is not big, just in the palm of the hand, hand grip ball, hard pinch, you can feel the pressure of grip ball to the fingers.Generally hold many times, can feel the palm tingling fever, then you will have comfortable feeling. Because when squeezing the ball hard, the flexible ball deformation fills the palm, the palm is loose and tight, the ball can effectively stimulate the main points of the palm, promote blood circulation, achieve the effect of exercise and healthy care Basic exercises: hold the ball completely in the palm, do ten times hand stretching exercises, first do the right hand exercise and then do the left hand exercise, alternate exercises. Package List： 5 x Hand Exercise Ball