Who made this signal. It has the letters "HS" written on the back of the housing:
(https://live.staticflickr.com/65535/48138361747_c469a4907e_c.jpg) (https://flic.kr/p/2gkPFQg)Mysterious HS logo (https://flic.kr/p/2gkPFQg) by thesignalman (https://www.flickr.com/photos/144426590@N04/), on Flickr
Horni Signal. They were bought my Marbelite in the 40s.
That's Highway Signal & Sign. IIRC, they usually have a blank parallelogram logo on the back, but some of them use this HS logo instead.