... the solid ball, because practicing without sound, named dumbbell. Light-weight dumbbells are 6,8,12,16 pounds (1 pound = 0 ... .4536 kilograms) and so on. The weight of heavy dumbbells 10,15,20,25,30 kg and ... increased weight, you need the coordination of multiple muscles, but also as a compound muscle action training. dumbbell weight lift equipment muscle strengthening equipment