You can choose your connection back or lower connection and the size. I took the 2.5" with back connection so I read the dial from the top. 1-2 bar Is the more appropriate it's quite useful to get the info in bar instead of just PSI as seen in the ebay auction.
I decided the quickest way to home in on correct pressure would be by taste. So I am adjusting the pressurestat until I get a good shot. Might as well trust my palate. Still too hot at this point, but starting to get good crema although burnt flavours still predominate.