Designed for both HO/O-Scale layouts. Miller Engineering's expanding line of window signs are a great addition to their roof top signs! Simple to install, ready-to-run and a pleasure to look at! They come on a clear background. Approximate measurements are 2" wide by 2.2" tall and can be trimmed as small as .825" wide x .9" tall. They run on 4.5 volts DC. Also compatible with Miller's AC Adapters and ME48040 converter module.