This is a common lamp that was mounted on switch stands that I built for some fellow C&O modelers. The model is in HO scale. The bottom is cored so it can be mounted on a clear plastic rod for illumination. Trim the lamps from the sprue with flush cutting pliers such as Xuron (it is the top of the lamp that is attached to the sprue) and use some 320 grit sandpaper to toke the sprue remanent down to the top of the lamp, at the small flange. For someone with real determination (like me) an array of four fiber optic light guides could be installed so the proper red/green display would be presented for the switch position. In larger scales this would not be much of a problem. A more rational approach would be to use a single fiber and just set the whole lamp for red (diverging) or green (straight).