one of four matching c. 1930's depression era american industrial galvanized steel experimental animal cage designed and fabricated by hoeltge brothers, inc., cincinnati, oh. hoeltge was a metal fabricating company that specialized in making animal research laboratory cages for various medical institutions. this cage was likely used to house mice. three sides of the lightweight cage are comprised of durable metal mesh. the backside is a single sheet of pressed and folded galvanied steel. the topmost edges protrude outward for sliding in and out of a larger rack that housed animal or mouse colonies. all four cages are identical, with very little to no rust evident. great overall condition, considering age. manufacturer markings are lightly embossed along the front. priced individually. salvaged from the old cook county hospital.