1.The dumbbells force the limbs to work unilaterally. Overcompensation is impossible with dumbbells, so they are an effective way to eliminate force imbalances. 2.Dumbbells can be used for a variety of exercises. Due to their size and versatility, they can be used to create a variety of movement patterns to develop specific tasks or force of movement. 3The knot on the bar allows your hand to grip the bar securely. -These weight plates are secure with star collars to them from slipping during exercise. 4.perfect for various warm-up sports and strength training such as arms, shoulders, abs, legs or back training. size:35*2.5cm Material:Steel + plastic colour:Black + red Package Contents: 2 * 35cmDumbbell bars 4 * black nuts Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.