Mine is a series 2000-0 with a max of .50 but a 2000-00 has max .25. Either works. I read by using tubing from the gauge to a piece of copper tubing that fits inside of the screw hole. I can take a picture later if necessary.
Thanks for all the helpful info. If you can take a picture, that would be great. One thing I have noticed, is that the glass hasn't turned black. Just the usual white on the upper right side