I had the $25 tool from Harder Steenbeck and when it was needed it was very helpful. A .20mm nozzle get get clogged before you have time to just blow the thing out with high PSI and some strong solvent. (That might not be a good idea for some brushes anyway - or so the good people at Chicago Airbrush tell me - some of the most expensive brushes have thin O-rings that don't really like something like lacquer thinner. I don't make the claim.) The flat blade is what makes the thing so effective - you can really clear out a gunked up nozzle - I find that sometimes I'll leave a little behind and the airbrush still works but it loses it's nice pattern. Anyway, for $5 it's a no-brainer.