Well, if you're talking Kohlert
immediately before WWII, they had the nice, big "VKS" keyguards. That kinda gives it away

.
If you're referring to the Mercedes-Benz-style keyguard on the low C key, there were a few companies that had them. Rampone is probably the most famous for that, although they had a metal circle smack in the middle for the key bumper. You could successfully argue that all the manufacturers that had that kind of guard were trying to get a little boost in sales from the Conn mystique.
There were quite a few companies that really went overboard with keyguards. Hey, it's very recognizable. At 50 feet, you might see the keyguard but not the name engraved on the bell.