Interesting points to note:
-Acrylic lenses predated Poly signals & Lexan lenses.
-Possibly the first Poly signal and first use of Lexan for lenses.
Although Horni at least experimented with Bakelite type signal housings.
-The first Durasigs used WingBOLTS not WingNUTS or later thmbscrews to hold the doors shut.
-The visors used the twist-n-lock install method
-The lens and reflector were gasketed together.
-The original configuration was yellow signals with black visors [and doors?]
