They used to be made by a company called Kauffman. Now they are made by Otter Messer, another German maker. A lot of variants are available now. A few years ago, Otter offered a brass handle that was nearly unobtanium for a year or so. There was one vendor in this country that had annexclusive and wanted an arm and a leg. I went to some lengths to get one from the manufacturer rather than pay the extortion.
Now they come in brass, copper, stainless, plus the original painted finish.
In WWII, these knives were popular with German soldiers, although they were never Wehrmacht issue. In due course, a lot of them ended up in the hands of GIs, who brought them home. In the fifties, they were favored by certain New York street gangs, and readily available in corner stores for about a buck a copy.