Advantages of free weights.
1. For small money comparatively much weight!
Disadvantages of these dumbbells.
1. For biceps training they are much too large and bulky, in the studio I lift the same weight and the weight is only half as large. Some exercise can not correct run clean.
2. Constantly loosen the wheels and everything is on the move. Passing does nothing bad, but the individual weights are no longer fixed and the nerves very quickly!