Development of the doublet lens by Churchill at Corning Glass Works allowed an electric light source to be more effective than with previous daytime colorlight signal designs. There are two main types of cases: the single case, where two or more lamps were contained within a single cast housing, and the modular light, where each lamp was an independent unit capable of being arranged into a signal of arbitrary configuration, including triangular. US&S has a popular single case type with its styles R/R-2, P-2/5 and N, while GRS offered their triangularly arranged Type G, with the Chicago Signal Company providing a similar version. Today's Safetrans Triangular is a copy of the GRS Type G but with vertically arranged double doors.
