TLB's Artista range features a narrow waist and I have flat feet which leave big gaping at the mouth of the shoes when I wear them. It's sad to say they look gorgeous but they don't look good on me.
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On the other hand, for their main line, it's interesting that for the same Alan last, same size, same model and merely different color/ leather, there's still gaping on the black one (left) but not the brown one (right).
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I have the same problem and I went for an E-width. A much better fit for my flat feet.