This is a parallel mount dial pointer (part #115903-1). It features a compact 3/4" x 1/8" rectangular mounting base designed to attach to a slider track or drive cable, extending a short 1/2-inch indicator needle parallel along slide-rule glass dial scales. This style was commonly used in compact tabletop radios and receiver units manufactured by companies like Philco, Zenith, RCA Victor, General Electric, and Crosley.