Stephenson was one of the first producers of radar speed detection devices. This one probably dates to the early-mid sixties, and consisted of a sleek, modern triangular(ish) metal box with speed gauge and controls and a seperate emitter/collector device that was hung on a rear window glass. On spotting a suspect, an officer would push the trigger button and read the speed off the analog meter.
Once again this is a company with very little history online, the company seems to have been in business from 1960-1971. I found the following at The History of the Radar Gun site.
Stephenson Company details; William H. Stephenson, President, Eatontown/Red Bank, New Jersey Radar speed measuring devices (Speedalyzer?), resuscitators, alcohol testing equipment (Breathalyzer? and Drunkometer?), rescue and first aid equipment.
In 1968, Stephenson Corp was acquired by and became of subsidiary of Bangor Punta Corp, a large conglomerate. In 1971, Robert P. Falconer became President, and it was part of the Smith & Wesson Public Security Group, inside Bangor Punta. (S&W was acquired by them in '65).
I was tempted to buy and try it out, but no idea if it worked and I wonder just how "dirty" the emissions might be.