the invention is several alternative means of differentiating head / gimbal assemblies that share a common arm . the alternative means are for at least one of the assemblies that shares a common arm using a different design ; varying the length from the mounting section to the slider ; changing the shape of the spring section ; varying the use and shape of raised flanges ; varying the use and shape of stiffeners ; using different openings ; using different formed features ; using various mass appendages ; and using a varying pattern of adhesive or glue dots .