“May contain XXX”, means that we cannot guarantee that the product is totally free from XXX, despite all reasonable precautions. An example would be “May contain nuts”. Due to the allergenic nature of nuts, we cannot say that a product is nut-free as it is manufactured in an environment where nuts are used. All precautions are in place, such as separate storage and full clean-down between products, but there is still a very small risk of cross-contamination.