While batteries have been around since the 1880s and the flashlight since the 1890s, flashlights became popular after World War I with the mass production of the small Mazda tungsten bulb.
Originally known as the Vest Pocket Mazda, or as the Folding Case Flash Light, they gained favor with sanitary inspectors because of their size and utility. The ones pictured above were patented in 1914. The smaller of the two (on the left) was manufactured by Franco USA and sold by the Interstate Electric Novelty Company in Brooklyn, New York.
These flashlights used radio batteries or B cells. They are made of nickel-plated brass and have a folding case design.
The larger of the two (on the right) was possibly made by the American Ever Ready Works and belonged to Raymond J. Chapman, principal sanitarian for the Metro District of the New Jersey State Department of Health.