with a succinct slogan which summed up the Hoover's cleaning action: 'It Beats...as it Sweeps...as it Cleans'. At this time, it referred to the action of the revolving brushes, which vibrated the carpet and helped loosen the trodden-in grit. This offered an advantage over competitors' machines, which used suction alone to remove dirt, and therefore were not as efficient as the Hoover. Seven years later, the famous slogan would adapt to even more significance. Hoover's business began to flourish, and, a year after Hoover acquired the patent from Spangler, he established a research and development department for his new business. By 1926, Hoover had developed the 'beater bar' - a metal bar attached to the rotating brush roll, situated in the floor nozzle cavity of the upright vacuum cleaner. Introduced on Models 543 and 700, the beater bars alternated with the sweeping brushes to vibrate the carpet while sucking. It provided a more distinct 'tap' than the bristle tufts used on the former machines, and led to a 101% increase in efficiency. This cleaning action was marketed by Hoover as "Positive Agitation". 'It Beats...as it Sweeps...as it Cleans' rang more true now than ever. In 1929, Hoover introduced the Model 200 Duster. This would be their first attempt at a cylinder cleaner. It used a Model 575 motor with a modified suction impeller, which was mounted on a unique aluminum body with runners, allowing the cleaner to be pulled behind the user. The Duster was produced for only three months and roughly 9,000 were made. Herbert W. Hoover, Sr. took over as president of the company in 1922 and as chairman of the board of the Hoover Company in 1932. 1930 saw the introduction of the world's first handheld vacuum cleaner, the Hoover Dustette. The good design and exceptional durability of these machines mean many are still in service today, some at over 80 years old. In 1932, Hoover introduced a new optional headlamp called the Hoover Hedlite on Models 425, 750 and 900. By March 1932, it had become standard equipment on Models 750 and 900, and a $5 extra-cost option on Model 425. The Hoover Hedlite illuminated the floor ahead of the cleaner, useful for dimly-lit rooms and corridors, and under furniture. Several new slogans mentioned the light, including 'It shows you the dirt you never knew you had!', and 'It lights where it's going...it's clean where it's