Metallic substance rubs off from the part of the whip (aluminum) which attaches to the mixer.  The wires are stainless steel though so are fine.  I see the newer models are all stainless steel & really want that.  But now I'm caught with a tough decision...buy a new whip which will eventually have metallic substance rub off or just buy a newer model when I spent hundreds to buy my current mixer?? (This review was collected as part of a promotion.)