There are 3 tiers or levels of gluten free. Less than <20ppm (parts per million), Less than 10ppm, and Less than 5ppm. If something is less than 20 ppm then the manufacturer can put on the label, "Gluten Free". However, this is not policed and unless an outside entity tests the product there is no way to verify it, so don't take the words, "gluten free" as to mean guaranteed. The second level or tier is less than <10ppm, this must be certified by a 3rd party, in our case it is GFCO. However, eBars has internally set the highest standard for gluten free testing and tests all it's products at <5ppm. Ebars, has never had a single positive test in it's 5 years history for gluten.