Although Dirk Fassbender has added to the gauge, the original is by Antti Pankonen.
Best to get it already attached to a model, so you can see how it hangs together.
Search the library for "Antti"
An example:
FS2004 (ACOF) - FS2004 HelicoptersFS2004 Philippine Air Force Eurocopter AS332 Super Puma
[ Download | View ]
Name: 332paf.zip
Size: 4,865,250 Date: 07-28-2012 Downloads: 1,677
Give it a try, it requires a little effort but gives good results once you get the hang of it.