Until recently, I'd never had a high-quality air chuck, so I decided to buy a tire inflator with an integrated manometer. The Hazet 9041-1 and the Metabo RF100 tire inflators are nearly identical in their design, using the same gauge and nearly the same main casting. I purchased one of each -- the Hazet from Amazon UK and the Metabo from Amazon Germany.
When they arrived, I found that both the Hazet and Metabo had the same European style of air quick-connect fitting installed (either the Obac type or the CEJN type -- I'm not sure which they were.) All of my other tools and air lines are using the Industrial interchange standard (which is also a MIL spec and ISO standard), so I had to change the quick-connect type on the inflator. I determined that the threading in the casting was neither NPT nor metric, but British Standard Pipe Parallel (BSPP) at 1/4" diamter. This is also known as "G" type thread, and has a pitch of nineteen threads per inch. Although it's an unusual combination, I was able to find Industrial male quick-connect fittings with male 1/4" BSPP thread. They're made by TST-Tamsan with the part number 023 EU 13, and sold by Allied Electronics under stock number R1007636. Note: As of January 2016, this part is no longer listed at Allied, and I'm not sure whether it's available at all.
Update 2020-04-30: A while back, I received an email pointing me to the original manufacturer of these inflators. They're produced by GAV Air Technology in Italy as the Model 60D.