Metal strips on Shimano road shoes?

I just bought a pair of Shimano R-151 road shoes (on sale at Performance for
$140 - 20% coupon), and noticed a series of parallel metallic strips on
their soles. I assume that these are visual aids in positioning the cleats
(I'm using SL-11 cleats for my DA pedals). But why metal or metallic? Is
this just to make them more visible, or do they somehow interact with some
sort of cleat positioning device that uses magnetic sensors? Or has Shimano
determined that they help with performance? ;-)

Just curious.

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