Look for the tag on the product which will have the size and other product information mainly inside the shoe that is behind the tongue of the shoe. Real Adidas shoes have tags with serial numbers for the left and right shoe. However, a fake product will have the same serial number on both shoes.

The real adidas Originals have different serial numbers on the left and right basket, unlike the fake ones. The serial number on the underside of the tab must match the serial number on the box. The brand uses its cloverleaf logo in a print on the tongue and not a sticker like the counterfeits.