2.25x3” pair of cardboard sheets with sealed left and right edges. At the center is a large oval opening. When held in the hand with thumb and fingers on the left and right edges, slight pressure applied in either direction causes the center photo to change between the 3 photographic images of Hoover, his running mate Curtis and view of U.S. Capitol. Very tiniest bit of age on the cardboard. Quite an interesting concept and a rare flasher device c. 1928. Only example we’ve seen.