late 1920's original wall mount interior freight elevator single-button indicator panel salvaged from a chicago factory complex. the cast bronze plaque was likely fabricated by or for the otis elevator company, new york. the plaque retains the original ruby red circular inset contains the words "in use" finished in black paint. the spring-loaded button was removed long ago. nicely aged surface patina. measures 5 1/2 x 2 3/8 inches.