Product/model number not appearing when selecting a product variation

When I download a product from Aliexpress to my site, the corresponding model/product number does not appear when you click on each color variation. I have gone through all the attributes and cannot see or find how to add this option. (see screenshots of an example of a mattress I downloaded and you can see the color code that appears on aliexpress is not appearing on my product page to the right of the “Color” title)

Thanks for your help!