Is it just me or is this extremely counterintuitive? From everything I've read you want steel to contact the rocks as it will resist the wear better, it's why @Fluxor provides stainless steel rash guards on his bumpers and sliders. Not to mention the irony of a heavy steel bumper and then making the skid of all things lightweight.
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It isn't the only thing that doesn't make much sense about that bumper.