I got one of them (slightly larger one, think about 34), and a bunch of digital gauges cheap on ebay from China.
Got two volt meters (one for starter/engine battery, other for winch), and the temp gauge.
The temp guage has a flat head screw on the back to a pre-set resistor I think with the idea to calibrate it.
They look good/ok, but accuracy is ****e.....I shouldve expected it from China I guess