The forearms make up almost 1/2 of your arms

without strong forearms overall arm symmetry and strength will be severely lacking

Well built forearms used to come from years of training and always took longer to develop because the forearms have always been trained indirectly whether it be with barbells, grip emphasis devices or wrist rollers.  The weight or tension that is being applied in these manners lies on the same plane as the gripping hands and is in such close proximity to the forearms that the inertia used to move the weight is not directly opposed to the forearms.  This in turn does not allow full activation of all the muscles groups that make up the forearms and wrist flexors.

The Monster E Z curl Bars incorporate a patented forearm and wrist strength training attachment that places the weight on a plane opposed to the gripping hands allowing a straight line of pull.  This applies tension directly to the forearms and wrist flexors making it 60-70% more efficient than barbells, wrist rollers or grip emphasis devices.