isn't that the house brand that NAPA sold? Might look on the back for date codes...otherwise, they're probably from the 50s-80s.
That's why I suggested looking for date codes...if SW made them, then there might be useful info stamped on the back.
Niehoff and SW were both Chicago based companies. Niehoff sold ignition components. I doubt they actually produced gauges. As above, they may well have private labeled gauges produced by SW.
They were in our line when I worked for BWD. I don't know if BWD/Niehoff still have them or not. I can't remember our vendor's name, but the quality was very good. They supplied a lot of gauges for the marine trade. I have them in one of my cars. Use them. .bjb
The temp & amp both say niehoff , the oil pressure says Rochester manufacturing , Rochester New York ?