I bought my paint ball yoke adapter off the internet and it works fine filling my Disco. Don't forget to buy an extention hose too.
We all know they are copied designs. I seriously doubt that they're alltested by the copier.
The only thing done is copy and paste the specs from the original.
So, if the one you buy says 3000 PSI...don't worry...just change the tag to 3500 PSI and you're OK.
Besides, the gauge goes up to 5000 PSI so it should be good right...

Seriously...It's just an aluminum or steel block with a couple of holes,screws, ando-rings. I think it would be blatantly obvious if it were inferior,
butyou can't tell that until you get it... since they copy the photo too!
If it has a 3000 PSI working pressure, the failure pressure is up around 5000 PSIand a few 100 PSI won't make a difference short or long term.
If there were problems with any of them, people would be posting flames like crazy.
To get something 100% tested by a reliable US manufacturer will cost you $$$, and that's only because they will be around to be sued.