Pringles have only about 42% potato content, with the remainder being wheat starch and flours (potato, corn, and rice) mixed with vegetable oils and an emulsifier.
In the UK High Court in July 2008, Proctor & Gamble (P & G) lawyers successfully argued against a value added tax (VAT) and Duties Tribunal decision that Pringles were not crisps, even though it said “Potato Crisps” on the container, as their actual potato content was only 42%. This exempted Pringles from the 17.5% VAT for potato chips and potato-derived snacks. In May, 2009 the Court of Appeal reversed the earlier decision.
Source: Wikipedia