MX Shoe Size (Mexican) refers to the Mexican shoe sizing system. It is commonly used in Mexico and differs slightly from US and European sizing. Here's a quick overview:

For men's shoes, The MX size is usually 1 to 1.5 sizes smaller than the equivalent US size.
For women's shoes, The MX size is often 1.5 to 2 sizes smaller than the equivalent US size.

For example:
A US men's size 9 is approximately an MX size 7.5–8.
A US women's size 8 is roughly an MX size 6–6.5.

The exact conversion can vary slightly by brand or manufacturer, so checking a specific size chart when shopping is always a good idea. Want me to find a conversion chart for you or help with a specific size?