Most Nike items will follow this rule if it contains the small serial code label. Look underneath the wash tag to find this reference.

Now let's get low with the Nike Blazer Lows. These sneakers are the epitome of casual cool. They generally run true to size but have a slightly roomier fit compared to the Mids and Highs. If you prefer a tighter fit, you might even consider going half a size down.

All authentic Nike shoes have a tag sewn into them with their size, barcode and model number on it. You will recognize it most easily by the barcode.