I own a few airbrushes, three or four chinese ones, (used for primer coverage and clearcoats)
I use harder stenbecks Ultra with .2 kit and Infinity CRPlus with .4 kit.
Then a Paasche Hsr for primer detailing.
The ultra is a good airbrush, but suffers one misfortune, the needle tip and cap design.
The CR plus and infinity range come with a different cap and push on tip cover, but nearly all use the same needle tip. This is a pinch tip design, which i think is totally imperative when spraying acrylics. Dry tips easily fixed!
But the Ultra range come with a solid cap/cover design which is very difficult to backflow and nearly impossible to quickly clean tip dry problems.
So here is the fix.
Whichever needle size you have (.2 or .4) all you need is the CRPlus or infinity cap and push on pimch type cover. They fit perfectly, and presto! A much more user friendly pinch tip on the Ultra.
Surprising that Harder Steenbeck dont list it as an option!!