Vintage Sun Super Tach. Why are they worth?

couple of options for you


Vintage Sunpro Super Tach II Tachometer Gauge Hot Rod Gasser | eBay

Sunpro Super Tech ii CP7903 chrome frame, white face red dial 21467079033 | eBay

3-3/8" Sun Super Tach II Tachometer White / Chrome Bezel CP7903 21467079033 | eBay