The Advertising Standards Authority (ASA), the U.K.'s advertising watchdog, has banned a marketing leaflet used by Reebok to promote its ZigTech shoes and apparel, arguing that it was confusing. The front of the leaflet featured Lewis Hamilton, the Formula One driver, holding up a ZigTech shoe, while the back cover copy stated that ZigTech apparel was engineered with Celliant fibers, which increased oxygen levels by 7 percent and therefore gave the wearer more energy. The ASA ruled that studies to back up these claims could not be objectively substantiated, and that Reebok had not made it clear to which products the claim referred. As the ASA saw it, consumers may infer that the claim referred to ZigTech footwear, which is not made with Celliant fibers.